424B5

This is an offering by FuelCell Energy, Inc. of $38,000,000 aggregate principal amount of its 8% senior convertible notes due 2018.

The notes will bear interest at a rate of 8% per annum. Interest on the notes will be payable in cash or, subject to certain limitations, in stock semi-annually in arrears on December 15 and June 15 of each year, beginning December 15, 2013. The notes will mature on June 15, 2018, unless earlier converted or repurchased by us. The notes will be our senior, unsecured obligations and will rank equal in right of payment with our senior unsecured debt, and will be senior in right of payment to our debt that is expressly subordinated to the notes, if any. The notes will be structurally subordinated to all debt and other liabilities and commitments of our subsidiaries and joint ventures and will be effectively junior to our secured debt to the extent of the assets securing such debt.

The notes will be convertible, at your option, into shares of our common stock initially at a conversion rate of 645.1613 shares per $1,000 principal amount of notes (equivalent to an initial conversion price of approximately $1.55 per share), subject to adjustment as described in this prospectus supplement, at any time on or prior to the close of business on the business day immediately preceding the maturity date of the notes. If a holder elects to convert its notes in connection with a non-stock change in control (as defined in this prospectus supplement), we will, in certain circumstances, increase the conversion rate for notes converted in connection with such non-stock change in control. Upon conversion, we will deliver shares of our common stock based on the conversion rate in effect on the conversion date.

Our common stock is listed on The NASDAQ Global Market under the symbol “FCEL”. On June 19, 2013, the last reported sale price of our common stock was $1.36 per share.

Our business and an investment in our securities involve significant risks. See “Risk Factors” beginning on page S-8 of this prospectus supplement and page 5 of the accompanying prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

We estimate the total expenses of this offering, excluding the underwriting commission, to be approximately $300,000.

We anticipate that delivery of the notes will be made on or about June 25, 2013, subject to customary closing conditions.

This document is in two parts. The first part is the prospectus supplement, which describes the specific terms of the securities we are offering and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus. The second part, the accompanying prospectus, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. This prospectus supplement and the accompanying prospectus and the documents incorporated by reference herein and therein are part of a shelf registration statement that we filed with the Securities and Exchange Commission. Under the shelf registration process, we may offer from time to time shares of our common stock and other securities up to an original aggregate amount of $150,000,000. This prospectus supplement and the accompanying prospectus and the documents incorporated by reference herein and therein include important information about us, our securities being offered and other information you should know before investing. You should read this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus and any related free writing prospectus that we authorized to be delivered to you, as well as the additional information described under “Where You Can Find Additional Information” on page S-36 of this prospectus supplement and “Incorporation of Certain Information by Reference” on page S-36 of this prospectus supplement before investing in our securities.

To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in the accompanying prospectus or in any document incorporated by reference that was filed with the SEC before the date of this prospectus supplement, on the other hand, you should rely on the information in this prospectus supplement. If any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in this prospectus supplement or the accompanying prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.

You should rely only on the information contained in this prospectus supplement, the accompanying prospectus, any related free writing prospectus that we authorized to be distributed to you and the documents incorporated by reference herein and therein. We have not, and the placement agents have not, authorized anyone to provide you with information that is different. If anyone provides you with different or inconsistent information, you should not rely on it. We are offering to sell and seeking offers to buy shares of our common stock only in jurisdictions where offers and sales are permitted. We are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information contained in this prospectus supplement, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus and any related free writing prospectus that we have authorized to be delivered to you is accurate only as of their respective dates, regardless of the time of delivery of such documents or of any sale of securities. Our business, financial condition, results of operations and prospects may have changed since those dates. You should not consider this prospectus supplement or the accompanying prospectus to be an offer or solicitation relating to the securities in any jurisdiction in which such an offer or solicitation relating to the securities is not authorized. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the common stock and the distribution of this prospectus outside the United States. Furthermore, you should not consider this prospectus supplement or the accompanying prospectus to be an offer or solicitation relating to the securities if the person making the offer or solicitation is not qualified to do so, or if it is unlawful for you to receive such an offer or solicitation.

Unless the context requires otherwise, in this prospectus supplement and the accompanying prospectus the terms “FuelCell,” “the Company,” “we,” “us,” “our” and similar names refer to FuelCell Energy, Inc and its subsidiaries.

PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights certain information about us, this offering and information appearing elsewhere in this prospectus supplement and in the accompanying prospectus and in the documents we incorporate by reference. This summary is not complete and does not contain all of the information that you should consider before investing in our notes. The following summary is qualified in its entirety by, and should be read in conjunction with, the more detailed information and financial statements and notes thereto appearing elsewhere in this prospectus supplement and the accompanying prospectus and incorporated by reference herein and therein. Before you decide to invest in our notes, to fully understand this offering and its consequences to you, you should carefully read the entire prospectus supplement and the accompanying prospectus carefully, including the risk factors beginning on page S-8 of this prospectus supplement and beginning on page 5 of the accompanying prospectus, and the consolidated financial statements and related notes included in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein.

FuelCell Energy, Inc.

Overview

We are a leading integrated fuel cell company with a growing global presence. We design, manufacture, install, operate and service ultra-clean, efficient and reliable stationary fuel cell power plants for distributed baseload power generation. Our power plants offer scalable on-site power and utility grid support, helping customers solve their energy, environmental and business challenges. Initially a research company, FuelCell Energy was founded in Connecticut in 1969 and became a publicly traded company in 1992. We reincorporated in Delaware in 1999 and began selling commercialized fuel cell power plants in 2003.

Our Company vision is to provide ultra-clean, highly efficient, reliable distributed generation baseload power at a cost per kilowatt hour that is less than the cost of grid-delivered electricity. Our power plants provide electricity that is priced competitively to grid-delivered electricity in certain high cost regions and our strategy is to continue to reduce costs, which is expected to lead to wider adoption of our power plants.

With fully commercialized ultra-clean fuel cell power plants and decades of experience in the industry, we are well positioned to grow our installed base of power plants. Our plants are operating in more than 50 locations worldwide and have generated more than 1.6 billion kilowatt hours (kWh) of electricity, which is equivalent to powering more than 145,000 average size U.S. homes for one year. Our installed base and steadily growing backlog exceeds 300 megawatts (MW).

Our customer base includes utility companies, municipalities, universities, government entities and businesses in a variety of commercial and industrial enterprises. Our leading geographic markets are South Korea and the United States, and we are pursuing expanding opportunities in Asia and Europe.

Our Direct FuelCell^® (DFC^®) power plants use a variety of available fuels to produce electricity electrochemically—without combustion—in a process that is highly efficient, quiet and produces virtually no pollutants. DFC power plants generate more power and fewer emissions for a given unit of fuel than combustion-based power generation of a similar size, making them economical and environmentally responsible power generation solutions. In addition to electricity, our DFC power plants produce high quality heat that can be used for heating, cooling and other purposes; when used in Combined Heat and Power (CHP) configurations, system efficiencies can reach 90 percent. Unlike solar and wind power, our DFC power plants operate continuously regardless of geography, weather or time of day.

We service two primary markets: ultra-clean power (fuel cells operating on clean natural gas) and renewable power (fuel cells operating on renewable biogas). Our strategy is to expand in the 11 distinct vertical submarkets we have identified and further penetrate our key geographic markets while continuing to reduce product costs and expand our services business created by our increasing installed base of power plants. The sale of higher volumes of our products will further reduce costs and increase margins.

Our executive offices are located at 3 Great Pasture Road, Danbury, Connecticut 06813. Our telephone number is (203) 825-6000. We maintain a web site at the following Internet address: www.fuelcellenergy.com. The information on our web site is not part of this prospectus.

As used in this prospectus, all degrees refer to Fahrenheit (F), and kilowatt and megawatt numbers designate nominal or rated capacity of the referenced power plant. As used in this prospectus, “kilowatt” (kW) means 1,000 watts; “megawatt” (MW) means 1,000,000 watts; and “kilowatt hour” (kWh) is equal to 1 kW of power supplied to or taken from an electric circuit steadily for one hour. All dollar amounts are in U.S. dollars unless otherwise noted.

THE OFFERING

The following summary contains basic information about this offering and the notes and is not intended to be complete. It does not contain all of the information that may be important to you. For a more complete understanding of all of the terms and provisions of the notes, please refer to the section of this prospectus supplement entitled “Description of the Notes.”


Issuer		FuelCell Energy, Inc. (the “Company,” “us” or “we”)

Securities Offered		$38 million aggregate principal amount of 8% Senior Unsecured Convertible Notes due June 15, 2018, which we often refer to as the notes.

Offering Price		Each note will be issued at a price of 100% of its principal amount.

Maturity		June 15, 2018, unless earlier converted or repurchased. The principal payable under the notes will be payable in cash.

Interest Rate		8% per year. Interest will be payable in arrears in cash or shares of the Company’s common stock, at the option of the Company, on December 15 and June 15 of each year, beginning December 15, 2013. If paid in shares, such shares will be valued at a 7.5% discount to market price. See “Description of the Notes—Interest Rate.”

Ranking		The notes will be senior unsecured obligations and will rank equal in right of payment with all of our future senior unsecured indebtedness. The notes will be effectively subordinated to our secured indebtedness to the extent of the value of the related collateral, any senior secured indebtedness that we may incur in the future, and structurally subordinated to senior secured indebtedness and other liabilities of our subsidiaries. As of April 30, 2013, we and our subsidiaries had $11.3 million of indebtedness outstanding, and approximately $138.9 million of other liabilities outstanding. All the indebtedness outstanding was secured and no indebtedness was at the subsidiary level.

Conversion Rights		You may convert your notes into shares of our common stock at any time prior to the close of business on the business day immediately preceding the maturity date.

		The notes will be convertible into shares of our common stock at an initial conversion rate of 645.1613 shares of common stock per $1,000 principal amount of the notes (equivalent to an initial conversion price of approximately $1.55 per share). The conversion rate, and thus the conversion price, may be adjusted under certain circumstances as described under “Description of the Notes—Conversion Rights—Conversion Rate Adjustments.”

Limitations on Conversion and Other Issuances of common stock Due to Market Regulation		We shall not be obligated to issue shares of our common stock upon conversion of the notes and will not be able to pay interest on the notes in shares of common stock to the extent the issuance of such


		shares of common stock would exceed, in the aggregate, 19.9% of our outstanding common stock on the date of this prospectus supplement (including shares of common stock issued as interest on the notes and as conversion of the notes), unless we obtain the prior approval of our stockholders (the “Exchange Cap”). We will settle our conversion and interest obligations, if any, in excess of this limitation in cash.

Limitation on Beneficial Ownership		Notwithstanding anything to the contrary, the notes shall not be convertible by you to the extent (but only to the extent) that you or any of your affiliates would beneficially own in excess of 4.99% of our outstanding common stock.

Change of Control Repurchase		If we undergo a change of control, we will offer to buy the notes at a premium. If a purchaser of FuelCell does not assume the obligations of the notes, you will be obligated to sell the notes to us at a premium. See “Description of the Notes—Repurchase Upon a Change of Control.”

Make-Whole Payments Upon Conversion		If you elect to convert some or all of your notes, in addition to the consideration upon conversion, you will receive cash or a number of additional common shares for the notes being converted equal to the aggregate amount of accrued and unpaid interest, plus interest that would have been payable on the converted notes through, but not including, the earlier of (i) the date that is three years after the conversion date and (ii) the maturity date if the notes had not been so converted. If paid in shares, such shares will be valued at a 7.5% discount to market price and will be subject to the 19.9% limitation described above.


Events of Default		If an event of default on the notes occurs, the principal amount of the notes, plus accrued and unpaid interest, may be declared immediately due and payable, subject to certain conditions set forth in the indenture. These amounts automatically become due and payable in the case of certain types of bankruptcy or insolvency events of default involving the Company or certain of its subsidiaries.

DTC Eligibility		The notes will be issued in fully registered book-entry form and will be represented by one or more permanent global notes without coupons. Global notes will be deposited with a custodian for and registered in the name of a nominee of The Depository Trust Company (“DTC”). Beneficial interests in global notes will be shown on, and transfers thereof will be effected only through, records maintained by DTC and its direct and indirect participants, and your interest in any global note may not be exchanged for certificated notes, except in limited circumstances described herein. See “Description of Notes—Form, Denomination and Registration—Global Notes, Book-Entry Form.”



Absence of a Public Market for the Notes		The notes will be a new issue of securities. We cannot assure you that any active or liquid market will develop for the notes.

Trading		We do not intend to apply for listing of the notes on any securities exchange.

Nasdaq Symbol for Our Common Stock		Our common stock is traded on the Nasdaq Global Market (NasdaqGM) under the symbol “FCEL.”

Use of Proceeds		We intend to use the net proceeds from the offering for project financing, market development, and general corporate purposes.

U. S. Federal Income Tax Considerations		Interest and distributions on the notes will be taxable. Prospective purchasers of the notes are urged to consult their own tax advisors concerning the U.S. Federal income tax consequences to them of acquiring, owning and disposing of our notes, as well as the application of state, local and foreign income and other tax laws.

Risk Factors		You should carefully consider all of the information contained or incorporated by reference in this prospectus supplement prior to investing in the notes. In particular, we urge you to carefully consider the information set forth under “Risk Factors” beginning on page S-8 of this prospectus supplement and the “Risk Factors” in the accompanying prospectus for a discussion of risks and uncertainties relating to us, our business and an investment in the notes.

FuelCell has filed a registration statement (including a prospectus) with the Securities and Exchange Commission for the offering to which this communication relates. Before you invest, you should read the prospectus in that registration statement, the preliminary prospectus supplement forming a part thereof and other documents that FuelCell has filed with the SEC for more complete information about FuelCell and this offering. You may get these documents for free by visiting EDGAR on the SEC web site at www.sec.gov. Alternatively, FuelCell or Lazard Capital Markets LLC will arrange to send you the prospectus if you request it by contacting FuelCell at (203) 825-6000, Attention Investor Relations, or Lazard at (800) 542-0970.

Investing in the notes involves risks. In addition, as a result of the conversion feature of the notes, a holder will also be exposed to the risks of owning our common stock, and the value of the notes may fluctuate with the value of our common stock. You should carefully consider the risks described below relating to an investment in notes and our common stock, as well as the risks relating to our business and all other information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus, in particular the risk factors included in our annual report on Form 10-K for the year ended October 31, 2012 and in our quarterly report on Form 10-Q for the quarter ended April 30, 2013, before making an investment decision. The risks and uncertainties described below, in the accompanying prospectus and in our other filings with the SEC incorporated by reference herein are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently consider immaterial may also adversely affect us. If any of the following risks occur, our business, financial condition or results of operations could be materially harmed. In such case, the value of the notes could decline and you may lose all or part of your investment.

We have incurred losses and anticipate continued losses and negative cash flow.

We have been transitioning from a contract research and development company to a commercial products developer, manufacturer and services provider. As such, we have not been profitable since our fiscal year ended October 31, 1997. We expect to continue to incur net losses and generate negative cash flows until we can produce sufficient revenues to cover our costs. We may never become profitable. Even if we do achieve profitability, we may be unable to sustain or increase our profitability in the future. For the reasons discussed in more detail below, there are substantial uncertainties associated with our achieving and sustaining profitability. We have, from time to time, sought financing in the public markets in order to fund operations. Our future ability to obtain such financing, if required, could be impaired by a variety of factors, including, but not limited to, the price of our common stock and general market conditions.

Our cost reduction strategy may not succeed or may be significantly delayed, which may result in our inability to deliver improved margins.

Our cost reduction strategy is based on the assumption that continued increases in production will result in economies of scale. In addition, our cost reduction strategy relies on advancements in our manufacturing process, global competitive sourcing, engineering design and technology improvements (including stack life and projected power output). Failure to achieve our cost reduction targets could have a material adverse effect on our results of operations and financial condition.

Our products compete with products using other energy sources, and if the prices of the alternative sources are lower than energy sources used by our products, sales of our products will be adversely affected. Volatility of electricity and fuel prices may impact sales of our products and services in the markets in which we compete.

Our DFC Power Plants operate using a variety of fuels, including natural gas, methanol, diesel, biogas, coal gas, coal mine methane, and propane. If these fuels are not readily available or if their prices increase such that electricity produced by our products costs more than electricity provided by other generation sources, our products would be less economically attractive to potential customers. In addition, we have no control over the prices of several types of competitive energy sources such as oil, gas or coal as well as local utility electricity costs. Significant decreases (or short term increases) in the price of these fuels or grid delivered prices for electricity could also have a material adverse effect on our business because other generation sources could be more economically attractive to consumers than our products.

The reduction or elimination of government subsidies and economic incentives for alternative energy technologies, including our fuel cell power plants, could reduce demand for our products and services, lead to a reduction in our revenues and adversely impact our operating results.

We believe that the near-term growth of alternative energy technologies, including our fuel cells, relies on the availability and size of government and economic incentives (including, but not limited to, the U.S. Federal ITC, the incentive programs in South Korea and state renewable portfolio standard programs). Many of these government incentives expire, phase out over time, exhaust the allocated funding, or require renewal by the applicable authority. In addition, these incentive programs could be challenged by utility companies, or for other reasons found to be unconstitutional, and/or could be reduced or discontinued for other reasons. The reduction, elimination, or expiration of government subsidies and economic incentives may result in the diminished economic competitiveness of our power plants to our customers and could materially and adversely affect the growth of alternative energy technologies, including our fuel cells, as well as our future operating results.

Financial markets worldwide have experienced increased volatility and instability which may have a material adverse impact on our Company, our customers and our suppliers.

Financial market volatility and instability affects both debt and equity markets. This may impact the amount of financing available to all companies, including companies with substantially greater resources, better credit ratings and more successful operating histories than ours. It is impossible to predict future financial market volatility and instability and the impact on our Company and it may have a materially adverse effect on us for a number of reasons, such as:

We have signed product sales contracts, long-term service agreements and power purchase agreements with customers subject to technology and operating risks as well as market conditions that may affect our operating results.

The Company applies the percentage of completion revenue recognition method to certain product sales contracts which are subject to estimates. On a quarterly basis, the Company performs a review process to help ensure that total estimated contract costs include estimates of costs to complete that are based on the most recent available information. The percentage of completion for the customer contracts based on this cost analysis is then applied to the total customer contract values to determine the total revenue to be recognized to date.

We have contracted under long-term service agreements with certain customers to provide service on our products over terms ranging from one to 20 years. Under the provisions of these contracts, we provide services to maintain, monitor, and repair customer power plants to meet minimum operating levels. Pricing for service contracts is based upon estimates of future costs including future stack replacements. While we have conducted tests to determine the overall life of our products, we have not run our products over their projected useful life prior to large-scale commercialization. As a result, we cannot be sure that our products will last to their expected useful life, which could result in warranty claims, performance penalties, maintenance and stack replacement costs in excess of our estimates and losses on service contracts.

The Company has one customer who purchases power under a Power purchase agreement (“PPA”), whereby the customer agrees to purchase power from our fuel cell power plants at negotiated rates. Electricity rates are generally a function of the customer’s current and future electricity pricing available from the grid. Should electricity rates decrease or operating costs increase from our original estimates, our results of operations could be negatively impacted. We are not required to produce minimum amounts of power under this PPA agreement. We provide termination rights by giving written notice to the customer, subject to certain exit costs.

We warranty our products for a specific period of time against manufacturing or performance defects. We accrue for warranty costs based on historical warranty claim experience, however actual future warranty expenses may be greater than we’ve assumed in our estimates. As a result, operating results could be negatively impacted should there be product manufacturing or performance defects in excess of our estimates.

Our products are complex and could contain defects and may not operate at expected performance levels which could impact sales and market adoption of our products or result in claims against us.

We develop complex and evolving products. Our initial installations were demonstration power plants intended to test the technology in real-world applications. We learned extensively from these demonstration installations, enhancing the technology and improving the operation of the power plants. Our first commercial Direct FuelCell power plant installation in 2003 had a rated power output of 250 kW and a 3 year stack life. Most of these 250 kW installations were terminated at contract conclusion or earlier as the costs were too high to justify continuation and the customer’s power needs did not support a megawatt-class power plant. Certain of these early product designs did not meet our expectations resulting in mixed performance history, impacting the adoption rate of our products. Costs are

lower for our newer megawatt-class plants compared to sub-megawatt plants due to scale. With the growing expertise gained from an expanding installed base, we continue to advance the capabilities of the fuel cell stacks and are now producing stacks with a rated power output of 350 kW and an expected five year life.

We have limited field operating experience on our products, and despite experience gained from our growing installed base and testing performed by us, our customers and our suppliers, issues may be found in existing or new products. This could result in a delay in recognition or loss of revenues, loss of market share or failure to achieve broad market acceptance. The occurrence of defects could also cause us to incur significant warranty, support and repair costs, could divert the attention of our engineering personnel from our product development efforts, and could harm our relationships with our customers. The occurrence of these problems could result in the delay or loss of market acceptance of our products and would likely harm our business. Defects or performance problems with our products could result in financial or other damages to our customers. From time to time, we have been involved in disputes regarding product warranty issues. Although we seek to limit our liability, a product liability claim brought against us, even if unsuccessful, would likely be time consuming and could be costly to defend. Our customers could also seek and obtain damages from us for their losses. We have reserved for potential damages related to performance problems, however actual results may be different than the assumptions used in our reserve calculations.

We compete on the basis of our products’ reliability, efficiency, environmental considerations and cost. Technological advances in alternative energy products or improvements in the electric grid or other sources of power generation, or other fuel cell technologies may negatively affect the development or sale of some or all of our products or make our products non-competitive or obsolete prior to commercialization or afterwards. Other companies, some of which have substantially greater resources than ours, are currently engaged in the development of products and technologies that are similar to, or may be competitive with, our products and technologies.

Several companies are involved in fuel cell development, although we believe we are the only domestic company engaged in significant manufacturing and commercialization of carbonate fuel cells. Emerging fuel cell technologies (and companies developing them) include PEM fuel cells (Ballard Power Systems, Inc.), phosphoric acid fuel cells (ClearEdge Power) and solid oxide fuel cells (LG, and Bloom Energy). Each of these competitors has the potential to capture market share in our target markets. There are also other potential fuel cell competitors internationally that could capture market share.

Other than fuel cell developers, we must also compete with companies that manufacture more mature combustion-based equipment, including various engines and turbines, and have well-established manufacturing, distribution, and operating and cost features. Electrical efficiency of these products can be competitive with our DFC Power Plants in certain applications. Significant competition may also come from gas turbine companies.

We have a large and influential stockholder, which may make it difficult for a third party to acquire our common stock.

POSCO currently owns approximately 16 percent of our outstanding common stock, which could make it difficult for a third party to acquire our common stock. POSCO is also a licensee of our technology and purchaser of our products. Therefore, it may be in their interests to possess substantial influence over matters concerning our overall strategy and technological and commercial development.

We have limited experience manufacturing our products on a commercial basis, which may adversely affect our planned increases in production capacity and our ability to satisfy customer requirements.

Our first commercial power plant installation was in 2003 so we have limited experience manufacturing our products on a commercial basis. With full utilization under its current configuration, our overall manufacturing process has a production capacity of 90 MW per year depending on product mix and other factors. We expect that we will further increase our manufacturing capacity based on market demand. We cannot be sure that we will be able to achieve any planned increases in production capacity. Also, as we scale up our production capacity, we cannot be sure that unplanned failures or other technical problems relating to the manufacturing process will not occur.

Even if we are successful in achieving our planned increases in production capacity, we cannot be sure that we will do so in time to satisfy the requirements of our customers. Our failure to develop advanced manufacturing capabilities and processes, or meet our cost goals, could have a material adverse effect on our business prospects, results of operations and financial condition.

Unanticipated increases or decreases in business growth may result in adverse financial consequences for us.

If our business grows more quickly than we anticipate, our existing and planned manufacturing facilities may become inadequate and we may need to seek out new or additional space, at considerable cost to us. If our business does not grow as quickly as we expect, our existing and planned manufacturing facilities would, in part, represent excess capacity for which we may not recover the cost; in that circumstance, our revenues may be inadequate to support our committed costs and our planned growth, and our gross margins, and business strategy would be adversely affected.

Our plans are dependent upon market acceptance of, as well as enhancements to, our products. Fuel cell systems represent an emerging market, and we cannot be sure that potential customers will accept fuel cells as a replacement for traditional power sources. As is typical in a rapidly evolving industry, demand and market acceptance for recently introduced products and services are subject to a high level of uncertainty and risk. Since the distributed generation market is still evolving, it is difficult to predict with certainty the size of the market and its growth rate. The development of a market for our products may be affected by many factors that are out of our control, including:

If a sufficient market fails to develop or develops more slowly than we anticipate, we may be unable to recover the losses we will have incurred in the development of our products and may never achieve profitability.

As we continue to expand markets for our products, we intend to continue offering power production guarantees and other terms and conditions relating to our products that will be acceptable to the marketplace, and continue to develop a service organization that will aid in servicing our products and obtain self-regulatory certifications, if available, with respect to our products. Failure to achieve any of these objectives may also slow the development of a sufficient market for our products and, therefore, have a material adverse effect on our results of operations and financial condition.

We are substantially dependent on a concentrated number of customers and the loss of any one of these customers could adversely affect our business, financial condition and results of operations.

We contract with a concentrated number of customers for the sale of products and for research and development contracts. This includes POSCO, which is a related party and owns approximately 16 percent of the outstanding common shares of the Company.

There can be no assurance that we will continue to achieve the current level of sales of our products to our largest customers. Even though our customer base is expected to increase and our revenue streams to diversify, a substantial portion of net revenues could continue to depend on sales to a limited number of customers. Our agreements with these customers may be cancelled if we fail to meet certain product specifications or materially breach the agreements, and our customers may seek to renegotiate the terms of current agreements or renewals. The loss of, or a reduction in sales to, one or more of our larger customers could have a material adverse effect on our business, financial condition and results of operations.

Our research and development contracts are subject to the risk of termination by the contracting party and we may not realize the full amounts allocated under the contracts due to the lack of Congressional appropriations.

A portion of our fuel cell revenues have been derived from long-term cooperative agreements and other contracts with the U.S. Department of Energy, the U.S. Department of Defense, the U.S. Navy, and other U.S. Government agencies. These agreements are important to the continued development of our technology and our products.

Generally, our government research and development contracts are subject to the risk of termination at the convenience of the contracting agency. Furthermore, these contracts, irrespective of the amounts allocated by the contracting agency, are subject to annual Congressional appropriations and the results of government or agency sponsored reviews and audits of our cost reduction projections and efforts. We can only receive funds under these contracts ultimately made available to us annually by Congress as a result of the appropriations process. Accordingly, we cannot be sure whether we will receive the full amounts awarded under our government research and development or other contracts. Failure to receive the full amounts under any of our government research and development contracts could materially and adversely affect our business prospects, results of operations and financial condition.

A negative government audit could result in an adverse adjustment of our revenue and costs and could result in civil and criminal penalties.

Government agencies, such as the Defense Contract Audit Agency, routinely audit and investigate government contractors. These agencies review a contractor’s performance under its contracts, cost structure, and compliance with applicable laws, regulations, and standards. If the agencies determine through these audits or reviews that we improperly allocated costs to specific contracts, they will not reimburse us for these costs. Therefore, an audit could result in adjustments to our revenue and costs.

Further, although we have internal controls in place to oversee our government contracts, no assurance can be given that these controls are sufficient to prevent isolated violations of applicable laws, regulations and standards. If the agencies determine that we or one of our subcontractors engaged in improper conduct, we may be subject to civil or criminal penalties and administrative sanctions, payments, fines, and suspension or prohibition from doing business with the government, any of which could materially affect our results of operations and financial condition.

The U.S. government has certain rights relating to our intellectual property, including restricting or taking title to certain patents.

Many of our U.S. patents relating to our fuel cell technology are the result of government-funded research and development programs. We own all patents resulting from research funded by our DOE contracts awarded to date, based on our “small business” status when each contract was awarded. Under current regulations, patents resulting from research funded by government agencies other than the DOE are owned by us, whether or not we are a “small business.”

Nine U.S. patents that we own have resulted from government-funded research and are subject to the risk of exercise of “march-in” rights by the government. March-in rights refer to the right of the U.S. government or a government agency to exercise its non-exclusive, royalty-free, irrevocable worldwide license to any technology developed under contracts funded by the government if the contractor fails to continue to develop the technology. These “march-in” rights permit the U.S. government to take title to these patents and license the patented technology to third parties if the contractor fails to utilize the patents. In addition, one of our DOE-funded research and development agreements also required us to agree that we will not provide to a foreign entity any fuel cell technology subject to that agreement unless the fuel cell technology will be substantially manufactured in the U.S.

We now qualify as a “Large Business”, which could adversely affect our rights to own future patents under DOE-funded contracts.

This year, we qualify as a “large business” under DOE contracts. This allows us to own the patents that we develop under new DOE contracts if we obtain a waiver from DOE. A “large business” under applicable government regulations generally consists of more than 500 employees averaged over a one year period. We will no longer own future patents we develop under new contracts, grants or cooperative agreements funded by the DOE, unless we obtain a patent waiver from the DOE. Should we not obtain a patent waiver and outright ownership, we would nevertheless retain exclusive rights to any such patents, so long as we continue to commercialize the technology covered by the patents.

We cannot assure you that we will enter into partnerships that are consistent with, or sufficient to support, our commercialization plans, and our growth strategy or that these relationships will be on terms favorable to us. Even if we enter into these types of relationships, we cannot assure you that the partners with which we form relationships will focus adequate resources on selling our products or will be successful in selling them. Some of these arrangements have or will require that we grant exclusive rights to companies in defined territories. These exclusive arrangements could result in our being unable to enter into other arrangements at a time when the partner with which we form a relationship is not successful in selling our products or has reduced its commitment to marketing our products. In addition, future arrangements may also include, the issuance of equity and warrants to purchase our equity, which may have an adverse effect on our stock price. To the extent we enter into partnerships or relationships, the failure of these partners to assist us with the deployment of our products may adversely affect our results of operations and financial condition.

We depend on third party suppliers for the development and supply of key raw materials and components for our products.

We use various raw materials and components to construct a fuel cell module, including nickel and stainless steel which are critical to our manufacturing process. We also rely on third-party suppliers for the balance-of-plant components in our products. Suppliers must undergo a qualification process, which takes four to twelve months. We continually evaluate new suppliers and we are currently qualifying several new suppliers. There are a limited number of suppliers for some of the key components of products. A supplier’s failure to develop and supply components in a timely manner, supply components that meet our quality, quantity or cost requirements, technical specifications, or our inability to obtain alternative sources of these components on a timely basis or on terms acceptable to us could harm our ability to manufacture our Direct FuelCell products. In addition, to the extent the processes that our suppliers use to manufacture components are proprietary; we may be unable to obtain comparable components from alternative suppliers.

We do not know whether we will be able to maintain long-term supply relationships with our critical suppliers, or secure new long-term supply relationships, or whether such relationships will be on terms that will allow us to achieve our objectives. Our business prospects, results of operations and financial condition could be harmed if we fail to secure long-term relationships with entities that will supply the required components for our Direct FuelCell products.

We depend on our intellectual property, and our failure to protect that intellectual property could adversely affect our future growth and success.

Failure to protect our existing intellectual property rights may result in the loss of our exclusivity or the right to use our technologies. If we do not adequately ensure our freedom to use certain technology, we may have to pay others for rights to use their intellectual property, pay damages for infringement or misappropriation, or be enjoined from using such intellectual property. We rely on patent, trade secret, trademark and copyright law to protect our intellectual property. In addition, we have licensed much of our intellectual property to carefully selected third parties, and we depend on those third parties to also protect our intellectual property rights. As of April 30, 2013, we had 116 current U.S. patents and 228 international patents covering our fuel cell technology (including patents licensed to FCES). The U.S. patents have an average remaining life of approximately 10.7 years.

Some of our intellectual property is not covered by any patent or patent application and includes trade secrets and other know-how that is not able to be patented, particularly as it relates to our manufacturing processes and engineering design. In addition, some of our intellectual property includes technologies and processes that may be similar to the patented technologies and processes of third parties. If we are found to be infringing third-party patents, we do not know whether we will be able to obtain licenses to use such patents on acceptable terms, if at all. Our patent position is subject to complex factual and legal issues that may give rise to uncertainty as to the validity, scope, and enforceability of a particular patent.

We cannot assure you that any of the U.S. or international patents owned by us or other patents that third parties license to us will not be invalidated, circumvented, challenged, rendered unenforceable or licensed to others, or any of our pending or future patent applications will be issued with the breadth of claim coverage sought by us, if issued at all. In addition, effective patent, trademark, copyright and trade secret protection may be unavailable, limited or not applied for in certain foreign countries.

We also seek to protect our proprietary intellectual property, including intellectual property that may not be patented or able to be patented, in part by confidentiality agreements and, if applicable, inventors’ rights agreements with our subcontractors, vendors, suppliers, consultants, strategic partners and employees. We cannot assure you that these agreements will not be breached, that we will have adequate remedies for any breach or that such persons or institutions will not assert rights to intellectual property arising out of these relationships. Certain of our intellectual property have been licensed to us on a non-exclusive basis from third parties that may also license such intellectual property to others, including our competitors. If our licensors are found to be infringing third-party patents, we do not know whether we will be able to obtain licenses to use the intellectual property licensed to us on acceptable terms, if at all.

If necessary or desirable, we may seek extensions of existing licenses or further licenses under the patents or other intellectual property rights of others. However, we can give no assurances that we will obtain such extensions or further licenses or that the terms of any offered licenses will be acceptable to us. The failure to obtain a license from a third party for intellectual property that we use at present could cause us to incur substantial liabilities, and to suspend the manufacture or shipment of products or our use of processes requiring the use of that intellectual property.

While we are not currently engaged in any intellectual property litigation, we could become subject to lawsuits in which it is alleged that we have infringed the intellectual property rights of others or commence lawsuits against others who we believe are infringing upon our rights. Our involvement in intellectual property litigation could result in significant expense to us, adversely affecting the development of sales of the challenged product or intellectual property and diverting the efforts of our technical and management personnel, whether or not that litigation is resolved in our favor.

Our future success will depend on our ability to attract and retain qualified management and technical personnel.

Our future success is substantially dependent on the continued services and on the performance of our executive officers and other key management, engineering, scientific, manufacturing and operating personnel, particularly Arthur Bottone, our Chief Executive Officer. The loss of the services of any executive officer, including Mr. Bottone, or other key management, engineering, scientific, manufacturing and operating personnel, could materially adversely affect our business. Our ability to achieve our commercialization plans will also depend on our ability to attract and retain additional qualified management and technical personnel. Recruiting personnel for the fuel cell industry is competitive. We do not know whether we will be able to attract or retain additional qualified management and technical personnel. Our inability to attract and retain additional qualified management and technical personnel, or the departure of key employees, could materially and adversely affect our development and commercialization plans and, therefore, our business prospects, results of operations and financial condition.

We may rapidly expand our manufacturing capabilities, accelerate the commercialization of our products and enter a period of rapid growth, which will place a significant strain on our senior management team and our financial and other resources. Any expansion may expose us to increased competition, greater overhead, marketing and support costs and other risks associated with the commercialization of a new product. Our ability to manage rapid growth effectively will require us to continue to improve our operations, to improve our financial and management information systems and to train, motivate and manage our employees. Difficulties in effectively managing issues presented by such a rapid expansion could harm our business prospects, results of operations and financial condition.

We are subject to various federal, state and local laws and regulations relating to, among other things, land use, safe working conditions, handling and disposal of hazardous and potentially hazardous substances and emissions of pollutants into the atmosphere. In addition, it is possible that industry-specific laws and regulations will be adopted covering matters such as transmission scheduling, distribution, and the characteristics and quality of our products, including installation and servicing. These regulations could limit the growth in the use of carbonate fuel cell products, decrease the acceptance of fuel cells as a commercial product and increase our costs and, therefore, the price of our products. Accordingly, compliance with existing or future laws and regulations could have a material adverse effect on our business prospects, results of operations and financial condition.

Utility companies may resist the adoption of distributed generation and could impose customer fees or interconnection requirements on our customers that could make our products less desirable.

Investor-owned utilities may resist adoption of distributed generation fuel cell plants as the power plants are disruptive to the utility business model that primarily utilizes large central generation power plants and associated transmission and distribution. On-site distributed generation that is on the customer-side of the electric meter competes with the utility. Distributed generation on the utility-side of the meter generally has power output that is significantly less than central generation power plants and may be perceived by the utility as too small to materially impact their business, limiting their interest. Additionally, perceived technology risk may limit utility interest in stationary fuel cell power plants.

Utility companies commonly charge fees to larger, industrial customers for disconnecting from the electric grid or for having the capacity to use power from the electric grid for back up purposes. These fees could increase the cost to our customers of using our Direct FuelCell products and could make our products less desirable, thereby harming our business prospects, results of operations and financial condition.

Several U.S. states have created and adopted, or are in the process of creating, their own interconnection regulations covering both technical and financial requirements for interconnection to utility grids. Depending on the complexities of the requirements, installation of our systems may become burdened with additional costs that might have a negative impact on our ability to sell systems. The Institute of Electrical and Electronics Engineers has been working to create an interconnection standard addressing the technical requirements for distributed generation to interconnect to utility grids. Many parties are hopeful that this standard will be adopted nationally to help reduce the barriers to deployment of distributed generation such as fuel cells; however this standard may not be adopted nationally thereby limiting the commercial prospects and profitability of our fuel cell systems.

We could be liable for environmental damages resulting from our research, development or manufacturing operations.

Our business exposes us to the risk of harmful substances escaping into the environment, resulting in personal injury or loss of life, damage to or destruction of property, and natural resource damage. Depending on the nature of the claim, our current insurance policies may not adequately reimburse us for costs incurred in settling environmental damage claims, and in some instances, we may not be reimbursed at all. Our business is subject to numerous federal, state, and local laws and regulations that govern environmental protection and human health and safety. We believe that our businesses are operating in compliance in all material respects with applicable environmental laws, however these laws and regulations have changed frequently in the past and it is reasonable to expect additional and more stringent changes in the future.

Our operations may not comply with future laws and regulations and we may be required to make significant unanticipated capital and operating expenditures. If we fail to comply with applicable environmental laws and regulations, governmental authorities may seek to impose fines and penalties on us or to revoke or deny the issuance or renewal of operating permits and private parties may seek damages from us. Under those circumstances, we might be required to curtail or cease operations, conduct site remediation or other corrective action, or pay substantial damage claims.

Our products use inherently dangerous, flammable fuels, operate at high temperatures and use corrosive carbonate material, each of which could subject our business to product liability claims.

Our business exposes us to potential product liability claims that are inherent in products that use hydrogen. Our products utilize fuels such as natural gas and convert these fuels internally to hydrogen that is used by our products to generate electricity. The fuels we use are combustible and may be toxic. In addition, our Direct FuelCell products operate at high temperatures and use corrosive carbonate material, which could expose us to potential liability claims. Although we have incorporated a robust design and redundant safety features in our power plants and have established and comprehensive safety, maintenance, and training programs in place, follow third-party certification protocols, codes and standards, and do not store natural gas or hydrogen at our power plants, we cannot guarantee there will not be accidents. Any accidents involving our products or other hydrogen-using products could materially impede widespread market acceptance and demand for our products. In addition, we might be held responsible for damages beyond the scope of our insurance coverage. We also cannot predict whether we will be able to maintain adequate insurance coverage on acceptable terms.

Since we market our products both inside and outside the U.S., our success depends in part, on our ability to secure international customers and our ability to manufacture products that meet foreign regulatory and commercial requirements in target markets. Sales to customers located outside the U.S. accounts for a significant portion of our consolidated revenue. Sales to customers in South Korea represent the majority of our international sales. We have limited experience developing and manufacturing our products to comply with the commercial and legal requirements of international markets. In addition, we are subject to tariff regulations and requirements for export licenses, particularly with respect to the export of some of our technologies. We face numerous challenges in our international expansion, including unexpected changes in regulatory requirements, potential conflicts or disputes that countries may have to deal with, fluctuations in currency exchange rates, longer accounts receivable requirements and collections, difficulties in managing international operations, potentially adverse tax consequences, restrictions on repatriation of earnings and the burdens of complying with a wide variety of international laws. Any of these factors could adversely affect our results of operations and financial condition.

We depend on relationships with strategic partners, and the terms and enforceability of many of these relationships are not certain.

We have entered into relationships with strategic partners for design, product development, sale and service of our existing products, and products under development, some of which may not have been documented by a definitive agreement. The terms and conditions of many of these agreements allow for termination by the partners. Termination of any of these agreements could adversely affect our ability to design, develop and distribute these products to the marketplace. We cannot assure you that we will be able to successfully negotiate and execute definitive agreements with any of these partners, and failure to do so may effectively terminate the relevant relationship.

If we fail to maintain an effective system of internal controls, we may not be able to accurately report our financial results or prevent fraud, which could harm our brand and operating results.

Effective internal controls are necessary for us to provide reliable and accurate financial reports and effectively prevent fraud. We have devoted significant resources and time to comply with the internal control over financial reporting requirements of the Sarbanes-Oxley Act of 2002. In addition, Section 404 under the Sarbanes-Oxley Act of 2002 requires that we assess, and that our auditors attest to, the design and operating effectiveness of our controls over financial reporting. Our compliance with the annual internal control report requirement for each fiscal year will depend on the effectiveness of our financial reporting and data systems and controls. Inferior internal controls could cause investors to lose confidence in our reported financial information, which could have a negative effect on the trading price of our stock and our access to capital.

Our results of operations could vary as a result of methods, estimates and judgments we use in applying our accounting policies.

The methods, estimates and judgments we use in applying our accounting policies have a significant impact on our results of operations (see “Critical Accounting Policies and Estimates” in Part II, Item 7). Such methods, estimates and judgments are, by their nature, subject to substantial risks, uncertainties and assumptions, and factors may arise over time that could lead us to reevaluate our methods, estimates and judgments.

As we gain experience in future periods, management will continue to reevaluate its estimates for contract margins, service agreements, loss reserves, warranty, performance guarantees, liquidated damages and inventory reserves. Changes in those estimates and judgments could significantly affect our results of operations and financial condition. We may also adopt changes required by the Financial Accounting Standards Board and the Securities and Exchange Commission.

The market price for our common stock has been and may continue to be volatile and subject to extreme price and volume fluctuations in response to market and other factors, including the following, some of which are beyond our control:

In the past, following periods of volatility in the market price of their stock, many companies have been the subjects of securities class action litigation. If we became involved in securities class action litigation in the future, it could result in substantial costs and diversion of management’s attention and resources and could harm our stock price, business prospects, results of operations and financial condition.

Provisions of Delaware and Connecticut law and of our charter and by-laws may make a takeover more difficult.

Provisions in our certificate of incorporation and by-laws and in Delaware and Connecticut corporate law may make it difficult and expensive for a third-party to pursue a tender offer, change in control or takeover attempt that is opposed by our management and board of directors. Public stockholders who might desire to participate in such a transaction may not have an opportunity to do so. These anti-takeover provisions could substantially impede the ability of public stockholders to benefit from a change in control or change in our management and board of directors.

Future sales of substantial amounts of our common stock could affect the market price of our common stock.

Future sales of substantial amounts of our common stock, or securities convertible or exchangeable into shares of our common stock, into the public market, including shares of our common stock issued upon exercise of options, or perceptions that those sales could occur, could adversely affect the prevailing market price of our common stock and our ability to raise capital in the future.

The rights of the Series 1 preferred shares and Series B preferred stock could negatively impact our cash flows.

The terms of the Series 1 preferred shares issued by FCE FuelCell Energy, Ltd. (“FCE Ltd.”), our wholly-owned, indirect subsidiary, provide rights to the holder, Enbridge Inc. (“Enbridge”), which could negatively impact us.

The provisions of the Series 1 Preferred Shares require that FCE Ltd. make annual dividend payments totaling Cdn. $1,250,000, including (i) annual dividend payments of Cdn. $500,000 and (ii) annual return of capital payments of Cdn. $750,000. These payments will end on December 31, 2020. Additional dividends accrue on cumulative unpaid dividends at a 1.25 percent quarterly rate, compounded quarterly, until payment thereof. On December 31, 2020 the amount of all accrued and unpaid dividends on the Series 1 Preferred Shares of Cdn. $21.1 million and the balance of the principal redemption price of Cdn. $4.4 million shall be paid to the holders of the Series 1 Preferred Shares. FCE Ltd. has the option of making dividend payments in the form of common stock or cash under the Series 1 Preferred Shares provisions.

We are also required to issue common stock to the holder of the Series 1 preferred shares if and when the holder exercises its conversion rights. The number of shares of common stock that we may issue upon conversion could be significant and dilutive to our existing stockholders. For example, assuming the holder of the Series 1 preferred shares exercises its conversion rights after July 31, 2020 and assuming our common stock price is $1.05 (our common stock closing price on April 30, 2013) and an exchange rate of Cdn. $1.00 to U.S.$1.00 at the time of conversion, we would be required to issue approximately 4,455,932 shares of our common stock.

The terms of the Series B preferred stock also provide rights to their holders that could negatively impact us. Holders of the Series B preferred stock are entitled to receive cumulative dividends at the rate of $50 per share per year, payable either in cash or in shares of our common stock. To the extent the dividend is paid in shares, additional issuances could be dilutive to our existing stockholders and the sale of those shares could have a negative impact on the price of our common stock. A share of our Series B preferred stock may be converted at any time, at the option of the holder, into 85.1064 shares of our common stock (which is equivalent to an initial conversion price of $11.75 per share), plus cash in lieu of fractional shares. Furthermore, the conversion rate applicable to the Series B preferred stock is subject to adjustment upon the occurrence of certain events.

We will significantly increase our leverage as a result of the sale of the notes.

In connection with the sale of the notes, we will incur new indebtedness of $38 million. The degree to which we will be leveraged could, among other things:

Our ability to meet our debt service obligations will depend upon our future performance, which will be subject to financial, business and other factors affecting our operations, many of which are beyond our control.

The terms of the notes will not include restrictive covenants and provide only limited protection in the event of a change of control.

The indenture under which the notes are issued will not contain any restrictive covenants that might protect you from several kinds of transactions that may adversely affect you. In particular, the indenture will not contain covenants that will limit our ability to pay dividends or make distributions on or redeem our capital stock and, therefore, may not protect you in the event of a highly leveraged transaction or other similar transaction. Nor will the indenture restrict the incurrence of indebtedness by us or our subsidiaries. The requirement that we offer to repurchase the notes upon a change of control is limited to the transactions specified in the definition of a “fundamental change” under “Description of the Notes—Repurchase at the Option of the Holder upon a Fundamental Change.”

Accordingly, we could enter into certain transactions, such as acquisitions, refinancings or recapitalizations, that could affect our capital structure and the value of the notes and our common stock but would not constitute a fundamental change under the notes.

We may be unable to repay or repurchase the notes, including following a change of control.

At maturity, the entire outstanding principal amount of the notes will become due and payable by us. Upon a change of control, we may be obligated to repurchase your notes at a premium over the principal amount of the notes, plus accrued and unpaid interest to, but excluding, the date of the repurchase of the notes. We cannot assure you that we will have enough funds or be able to arrange for additional financing to pay the principal at maturity or to repurchase the notes or that our then-existing debt agreements will permit us to repay the principal amount at maturity or repurchase the notes.

Our failure to repay the notes at maturity or to repurchase notes would constitute an event of default under the indenture that governs the notes and may also constitute an event of default under any other indenture or other agreement governing then-existing indebtedness, which could prevent us from repurchasing the notes. If a change of control occurred and accelerated any other then-existing indebtedness, we cannot assure you that we would have sufficient financial resources, or be able to arrange for additional financing, to repay the principal amount at maturity or pay the repurchase price for the notes and amounts due under any other indebtedness.

Provisions of the notes could discourage an acquisition of us by a third party.

Certain provisions of the notes could make it more difficult or more expensive for a third party to acquire us. Upon the occurrence of certain transactions constituting a change of control, we would be obligated to offer to purchase the notes, at a cash repurchase price equal to a premium over the principal amount plus accrued and unpaid interest on the notes.

The conversion rate of the notes may not be adjusted for all dilutive events that may adversely affect the trading price of the notes or our common stock issuable upon conversion of the notes.

The conversion rate of the notes is subject to adjustment upon certain events, including the issuance of stock dividends on our common stock, the issuance of rights or warrants, subdivisions, combinations, distributions of capital stock, indebtedness or assets, cash dividends and issuer tender or exchange offers as described under “Description of the Notes—Conversion Rights—Conversion Rate Adjustments.” The conversion rate will not be adjusted for certain other events, including, for example, in issuance of stock for cash that may adversely affect the trading price of the notes or the common stock issuable upon conversion of the notes.

There is currently no public market for the notes, and an active trading market may not develop for the notes. The failure of a market to develop for the notes could adversely affect the liquidity and value of your notes.

The notes are a new issue of securities, and there is no existing market for the notes. We do not intend to apply for listing of the notes on any securities exchange or other stock market. Although we have been advised by the underwriters of the notes that they intend to make a market in the notes, they are not obligated to do so and may discontinue market making at any time without notice. A market may not develop for the notes, and there can be no assurance as to the liquidity of any market that may develop for the notes. If an active, liquid market does not develop for the notes, the market price and liquidity of the notes may be adversely affected. If any of the notes are traded after their initial issuance, they may trade at a discount from their initial offering price.

The liquidity of the trading market, if any, and future trading prices of the notes will depend on many factors, including, among other things, the market price of our common stock, prevailing interest rates, our operating results, financial performance and prospects, the market for similar securities and the overall securities market, and may be adversely affected by unfavorable changes in these factors. Historically, the market for convertible debt has been subject to disruptions that have caused volatility in prices. It is possible that the market for the notes will be subject to disruptions which may have a negative effect on the holders of the notes, regardless of our operating results, financial performance or prospects. .

If you hold notes, you will not be entitled to any rights with respect to our common stock, but you will be subject to all changes made with respect to our common stock.

If you hold notes, you will not be entitled to any rights with respect to our common stock (including, without limitation, voting rights and rights to receive any dividends or other distributions on our common stock), but you will be subject to all changes affecting our common stock. You will have rights with respect to our common stock only if you convert your notes, which you are permitted to do only in limited circumstances described herein. For example, in the event that an amendment is proposed to our articles of incorporation or bylaws requiring stockholder approval and the record date for determining the stockholders of record entitled to vote on the amendment occurs prior to delivery of our common stock to you, you will not be entitled to vote on the amendment, although you will nevertheless be subject to any changes in the powers, preferences or rights of our common stock.

Conversion of the notes will dilute the ownership interest of existing stockholders, including holders who had previously converted their notes.

To the extent we issue common stock upon conversion of the notes, the conversion of some or all of the notes will dilute the ownership interests of existing stockholders, including holders who had previously converted their notes. Any sales in the public market of the common stock issuable upon such conversion could adversely affect prevailing market prices of our common stock. In addition, the existence of the notes may encourage short selling by market participants because the conversion of the notes could depress the price of our common stock. If all of the interest payments on the notes were paid in shares of common stock at an assumed price of $1.36 per share, the last reported sale price on June 18, 2013, then we would issue an aggregate of 12,082,671 shares of common stock.

The notes are subject to certain limitations on conversion, and to the issuance of common stock to satisfy redemption and interest payment obligations.

We may not affect any conversion of a note, and you do not have the right to convert any portion of a note, to the extent that after giving effect to such conversion, you (and your affiliates whose ownership of securities is not disaggregated in accordance with SEC Release No. 34-39538) would beneficially own in excess of 4.99% of the number of shares of our common stock outstanding immediately after giving effect to such conversion.

In addition, Nasdaq Rule 5635(d) could prevent us from issuing shares of our common stock at prices below the market price on the date of this prospectus supplement for purposes of satisfying redemption and interest payment obligations if the total number of shares so issued equals 20% or more of our common stock outstanding on the date of this prospectus supplement. If limited by this rule, we will make these payments in cash and not in shares of our common stock.

The notes may not be rated or may receive a lower rating than anticipated.

We do not intend to seek a rating on the notes. However, if one or more rating agencies rates the notes and assigns the notes a rating lower than the rating expected by investors, or reduces its rating in the future, the market price of the notes and our common stock could be reduced.

The notes are effectively subordinated to our secured debt and to all liabilities of our subsidiaries.

The notes will be effectively subordinated to our secured indebtedness to the extent of the value of the related collateral. None of our subsidiaries will guarantee our obligations under, or have any obligation to pay amounts due on, the notes. As a result, the notes will be “structurally subordinated” to all indebtedness and other liabilities, including trade payables and lease obligations, of our existing and future subsidiaries (unless such indebtedness is by its terms subordinated to the notes). In addition, the notes are not secured by any of our assets or those of our subsidiaries. As a result, the notes will be effectively subordinated to any secured debt that we or our subsidiaries incur. In the event of our bankruptcy, liquidation or reorganization or upon acceleration of the notes, payment on the notes could be less, ratably, than on any secured indebtedness. We may not have sufficient assets remaining to pay amounts due on any or all of the notes then outstanding.

Our management has broad discretion over the use of proceeds from this offering.

Our management has significant flexibility in applying the proceeds that we receive from this offering. Because the proceeds are not required to be allocated to any specific investment or transaction, you cannot determine the value or propriety of our management’s application of the proceeds on our behalf. In addition, the proceeds of this offering may not generate a favorable return for us.

Some of the statements contained in this prospectus supplement or incorporated by reference into this prospectus supplement are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act, and are subject to the safe harbor created by the Securities Litigation Reform Act of 1995. We have based these forward-looking statements largely on our expectations and projections about future events and financial trends affecting the financial condition and/or operating results of our business. Words such as “anticipates,” “expects,” “intends,” “plans,” “believes,” “seeks,” “estimates,” the negative of these words, or similar expressions are intended to identify such forward-looking statements. These statements are not guarantees of future performance and are subject to certain risks, uncertainties and assumptions that are difficult to predict; therefore, actual results may differ materially from those expressed or forecasted in any forward-looking statements. The risks and uncertainties include those noted under the heading “Risk Factors” below, in the filings incorporated herein by reference and in the accompanying prospectus. There are important factors that could cause actual results to be substantially different from the results expressed or implied by these forward-looking statements including, among other things:

We do not intend to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. Past financial or operating performance is not necessarily a reliable indicator of future performance, and you should not use our historical performance to anticipate results or future period trends.

We estimate that the net proceeds to us from this offering, after deducting the underwriting discount related to the offering of the notes and estimated offering expenses payable by us, will be approximately $35.6 million, after deducting the estimated underwriting discounts and commissions and estimated offering expenses payable by us.

We currently intend to use the net proceeds of this offering (including any resulting from the exercise of the additional sale option) for project financing, market development, and general corporate purposes. General corporate purposes may include capital expenditures, repayment of debt, payment of dividends and any other purposes. While we have estimated the particular uses for the net proceeds of this offering, we have not determined the amounts we plan to spend on any of the areas listed above or the timing of these expenditures. As a result, our management will have broad discretion to allocate the net proceeds from this offering for any purpose, and investors will be relying on the judgment of our management with regard to the use of these net proceeds. Pending use of the net proceeds as described above, we intend to invest the net proceeds in money-market funds or U.S. treasuries until we use them for their stated purpose.

The ratio of our earnings to fixed charges are set forth below for each of the periods indicated.

For purposes of calculating the ratios of earnings to fixed charges, (i) fixed charges consist of interest on debt, amortization of discount on debt, capitalized interest, and preferred dividends and (ii) earnings consist of pre-tax income from operations and fixed charges (excluding capitalized interest) and include the amortization of capitalized interest.

The following table sets forth our combined cash and cash equivalents, total debt and owners’ equity as of April 30, 2013 on an (i) actual basis, and (ii) as adjusted basis to reflect the sale of $38 million aggregate principal amount of notes in this offering.

You should read this table in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our unaudited interim consolidated financial statements and the notes to those financial statements appearing in our Quarterly Report on Form 10-Q filed with the SEC for the period ended April 30, 2013, and the subsequently filed Quarterly Reports on Form 10-Q and Annual Reports on Form 10-K, which are incorporated by reference into this prospectus supplement.

We have never declared or paid any cash dividends on our capital stock. We currently intend to retain all available funds and any future earnings to finance the growth and development of our business and do not anticipate paying any cash dividends in the foreseeable future.

The notes will be issued under an indenture dated as of June 25, 2013, between FuelCell Energy, Inc., as issuer, and US Bank National Association, as trustee, as supplemented by a supplemental indenture to be dated as of June 25, 2013, which together we refer to as the indenture.

The following description is only a summary of the material provisions of the notes and the indenture. We urge you to read the indenture in its entirety because it, and not this description, defines your rights as a holder of the notes. You may request copies of the indenture as set forth under the caption “Where You Can Find Additional Information.”

When we refer to “we,” “our” or “us” in this section, we refer only to FuelCell Energy, Inc. and not its subsidiaries.

Neither we nor any of our subsidiaries will be subject to any financial covenants under the indenture. Neither we nor any of our subsidiaries will be restricted under the indenture from paying dividends or issuing or repurchasing our securities. You are not afforded protection under the indenture in the event of a highly leveraged transaction or a change in control of us, except to the extent described below under “—Repurchase upon a Change of Control”.

No sinking fund is provided for the notes and the notes will not be subject to defeasance.

The notes initially will be issued in book-entry form only in denominations of $1,000 principal amount and whole multiples thereof. Beneficial interests in the notes will be shown on, and transfers of beneficial interests in the notes will be effected only through, records

maintained by The Depository Trust Company, or DTC, or its nominee, and any such interests may not be exchanged for certificated notes except in limited circumstances. For information regarding conversion, registration of transfer and exchange of global notes held in DTC, see “—Form, Denomination and Registration—Global Notes, Book-Entry Form.”

If certificated notes are issued, you may present them for conversion, registration of transfer and exchange, without service charge, at our office or agency in New York City, which will initially be the office or agency for service of process of the trustee in New York City.

We may, without the consent of the holders of the notes, increase the principal amount of the notes by issuing additional notes in the future on the same terms and conditions, except for any differences in the issue price and interest accrued prior to the issue date of the additional notes; provided that such differences do not cause the additional notes to constitute a different class of securities than the notes for U.S. federal income tax purposes; and provided further that the additional notes have the same CUSIP number as the notes offered hereby. The notes offered by this prospectus supplement and the accompanying prospectus and any additional notes would rank equally and ratably and would be treated as a single class for all purposes under the indenture. No additional notes may be issued if any event of default has occurred and is continuing.

On the maturity date, each holder will be entitled to receive on such date $1,000 in cash for each $1,000 in principal amount of notes, together with accrued and unpaid interest to, but not including, the maturity date. With respect to global notes, principal and interest will be paid to DTC in immediately available funds. With respect to any certificated notes, principal and interest will be payable at our office or agency in New York City, which initially will be the office or agency for service of process of the trustee.

The notes will be senior unsecured obligations and will rank equal in right of payment with all of our future senior unsecured indebtedness. The notes will be effectively subordinated to our secured indebtedness to the extent of the value of the related collateral, any senior secured indebtedness that we may incur in the future, and structurally subordinated to senior secured indebtedness and other liabilities of our subsidiaries.

As of April 30, 2013, we and our subsidiaries had $11.3 million of indebtedness outstanding, and approximately $138.9 million of other liabilities outstanding. All the indebtedness outstanding was secured and no indebtedness was at the subsidiary level.

The notes will bear interest at a rate of 8% per annum. Interest will accrue from June 25, 2013 or from the most recent date to which interest has been paid or duly provided for. We will pay interest semi-annually, in arrears, in shares of our common stock, provided that the Equity Conditions are met, or at our option cash on June 15 and December 15 of each year, commencing on December 15, 2013, to holders of record at 5:00 p.m., New York City time, on the preceding May 31 and November 30, respectively (each, an “Interest Date”). Upon the occurrence of any event of default, until all such events of default have been cured, the notes will bear a default interest rate of 12% per annum.

To the extent that we pay interest in shares of our common stock, the number of shares (the “Dividend Shares”) will be based upon a price equal to a 7.5% discount to the average VWAP for our common stock for the ten Trading Days prior to the applicable Interest Date. On or before the eleventh (11th) Trading Day before the applicable Interest Date, we shall notify the holders of the notes whether we will pay interest in Dividend Shares or if we have elected to pay in cash; provided that, if no such notice is given, then we shall be deemed to have certified that the Equity Conditions are met and that we intend to pay such interest in Dividend Shares. On or before the third (3rd) Trading Day following the Interest Date, we shall (X) provided that our transfer agent is participating in The Depository Trust Company (“DTC”) Fast Automated Securities Transfer Program, credit the number of Dividend Shares to which each holder is entitled to such holder’s or its designee’s balance account with DTC through its Deposit/Withdrawal at Custodian system, or (Y) if the transfer agent is not participating in the DTC Fast Automated Securities Transfer Program, issue and dispatch by overnight courier to each holder, a certificate, registered in our share register in the name of such holder or its designee, for the number of Dividend Shares to which such holder is entitled pursuant to such exercise. Each holder entitled to receive interest in Dividend Shares on an Interest Date shall be treated for all purposes as the record holder of such shares of our common stock on the applicable Interest Date, irrespective of the date such Dividend Shares are credited to the holder’s DTC account or the date of delivery of the certificates evidencing such Dividend Shares, as the case may be. No fractional shares of our common stock are to be issued upon the issuance of Dividend Shares, but rather the number Dividend Shares to be issued shall be rounded up to the nearest whole number. The Company shall pay any and all taxes which may be payable with respect to the issuance and delivery of Dividend Shares.

Interest will be calculated on the basis of a 360-day year consisting of twelve 30-day months. If a payment date is not a business day, payment will be made on the next succeeding business day, and no additional interest will accrue thereon.

“Trading Day” means any day on which our common stock is traded on the Nasdaq Global Market, or, if the Nasdaq Global Market is not the principal trading market for our common stock, then on the principal securities exchange or securities market on which our common stock is then traded; provided that “Trading Day” shall not include any day on which our common stock is scheduled to trade on such exchange or market for less than 4.5 hours or any day that our common stock is suspended from trading during the final hour of trading on such exchange or market (or if such exchange or market does not designate in advance the closing time of trading on such exchange or market, then during the hour ending at 4:00:00 p.m., New York time).

“VWAP” means the dollar volume-weighted average price for our common stock on the Nasdsaq Global Market (or a successor market) during the period beginning at 9:30:01 a.m., New York time (or such other time as the Trading Market publicly announces is the official open of trading), and ending at 4:00:00 p.m., New York time (or such other time as the Trading Market publicly announces is the official close of trading), as reported by Bloomberg, L.P. through its “Volume at Price” function or, if the foregoing does not apply, the dollar volume-weighted average price of such security in the over-the-counter market on the electronic bulletin board for such security during the period beginning at 9:30:01 a.m., New York time (or such other time as the Trading Market publicly announces is the official open of trading), and ending at 4:00:00 p.m., New York City Time (or such other time as the Trading Market publicly announces is the official close of trading), as reported by Bloomberg, L.P., or, if no dollar volume-weighted average price is reported for such security by Bloomberg, L.P. for such hours, the average of the highest closing bid price and the lowest closing ask price of any of the market makers for such security as reported in the “pink sheets” by OTC Markets Group Inc. (formerly Pink Sheets LLC). If the VWAP cannot be calculated for the Common Stock on a particular date on any of the foregoing bases, the VWAP of the Common Stock shall be the fair market value of the Common Stock on such date as determined by our Board of Directors in good faith.

Holders may convert their notes into shares of our common stock at any time prior to the close of business on the business day immediately preceding the maturity date based on an initial conversion rate of 645.1613 shares of common stock per $1,000 principal amount of notes (equivalent to an initial conversion price of approximately $1.55 per share), unless earlier repurchased by us, at your option, as set forth under “—Repurchase at the Option of the Holder upon a Fundamental Change.” The conversion rate will be subject to adjustment as described below.

Except as provided in the next two paragraphs, upon conversion, you will not receive any separate cash payment of accrued and unpaid interest on the notes being converted. We will not issue fractional shares of our common stock upon conversion of the notes, but rather the number shares of common stock to be issued shall be rounded up to the nearest whole number. Accrued tax original issue discount, if any, will be deemed to be paid in full with the shares of our common stock issued upon conversion, rather than cancelled, extinguished or forfeited. Any accrued and unpaid interest and any applicable make-whole amount shall be paid in shares of our common stock or, at our option, in cash as set forth under “—Interest and Make-Whole Payments.”

Except as described under “—Conversion Rate Adjustments,” we will not make any payment or other adjustment for dividends on any common stock issuable upon conversion of the notes.

If you hold a beneficial interest in a global note, to convert you must deliver to DTC the appropriate instruction form for conversion pursuant to DTC’s conversion program.

The conversion date will be the date on which you have satisfied all of the foregoing requirements. The notes will be deemed to have been converted immediately prior to 5:00 p.m., New York City time, on the conversion date. Once delivered, a conversion notice shall be irrevocable.

You will not be required to pay any taxes or duties relating to the issuance or delivery of our common stock if you exercise your conversion rights.

Settlement of a conversion of notes into shares of our common stock will occur on the third trading day following the applicable conversion date. We will treat the persons entitled to receive the shares of our common stock issuable upon a conversion of any note for all purposes as the record holder or holders of such shares of our common stock on the applicable conversion date, irrespective of the date such shares of our common stock are credited to the holder’s DTC account or the date of delivery of the certificates evidencing such shares of our common stock, as the case may be.

For purposes of clause (3) above, “current market price” means the average closing sale price of our common stock for the 10 consecutive trading day period ending at the close of business of the trading day immediately prior to the ex-dividend date for the distribution requiring such computation.

The “closing sale price” of a share of our common stock on any trading day means the closing sale price of such security (or if no closing sale price is reported, the average of the closing bid and closing ask prices or, if more than one in either case, the average of the average closing bid and the average closing ask prices) on such day as reported in composite transactions for the principal U.S. securities exchange (or if not so listed, on the principal regional securities exchange) on which our common stock is traded or, if our common stock is not listed on a U.S. national or regional securities exchange, as reported by OTC Markets Group Inc. (formerly Pink Sheets LLC) or its successor entity. In the absence of such a quotation, the closing sale price will be determined by an independent nationally recognized securities dealer retained by us and reasonably acceptable to the trustee for that purpose. The closing sale price will be determined without reference to extended or after hours trading. The “conversion price” on any day will equal $1,000 divided by the conversion rate in effect on that day.

To the extent that any rights plan adopted by us is in effect upon conversion of the notes into common stock, you will receive, in addition to the common stock, the rights under the applicable rights agreement unless the rights have separated from our common stock at the time of conversion of the notes, in which case, the conversion rate will be adjusted as if we distributed to all holders of our common stock shares of our capital stock, evidences of indebtedness or assets as described above in clause (5).

In cases where the fair market value of assets, debt securities or certain rights, warrants or options to purchase our securities, applicable to one share of common stock, distributed to stockholders:

rather than being entitled to an adjustment in the conversion price, the holder of a note will be entitled to receive upon conversion, in addition to the shares of common stock, the kind and amount of assets, debt securities or rights, warrants or options comprising the distribution that such holder would have received if such holder had converted such notes immediately prior to the record date for determining the stockholders entitled to receive the distribution.

Except as stated above, we will not adjust the conversion rate for the issuance of our common stock or any securities convertible into or exchangeable for our common stock or carrying the right to purchase any of the foregoing.

In the event that we distribute shares of capital stock of a subsidiary of ours pursuant to clause (4) above, the conversion rate will be adjusted, if at all, based on the market value of the subsidiary stock so distributed relative to the market value of our common stock, in each case over a measurement period following the distribution.

and the holders of our common stock receive stock, other securities or other property or assets (including cash or any combination thereof) with respect to or in exchange for their common stock, then each outstanding note will, without the consent of any holders of the notes, become convertible only into the consideration the holders of the notes would have received if they had converted their notes based on the applicable conversion rate immediately prior to such reclassification, change, consolidation, merger, sale, lease, transfer, conveyance or other disposition (assuming such holder of common stock received proportionately the same consideration received by all common stock holders in the aggregate). In the event holders of our common stock have the opportunity to elect the form of consideration to be received in such transaction, then from and after the effective date of such transaction, the notes shall be convertible into the consideration that a majority of the holders of our common stock who made such an election received in such transaction. We may not become a party to any such transaction unless its terms are consistent with the foregoing.

If a taxable distribution to holders of our common stock or other transaction occurs that results in any adjustment of the conversion rate (including an adjustment at our option), you may, in certain circumstances, be deemed to have received a distribution subject to U.S. income tax as a dividend. In certain other circumstances, the absence of an adjustment may result in a taxable dividend to the holders of our common stock. See “Material United States Federal Income Tax Considerations.”

We will not be required to make any adjustment in the conversion rate unless the adjustment would require a change of at least 1% in the conversion rate. However, we will carry forward any adjustment that is less than 1% of the conversion rate, take such carried-forward adjustments into account in any subsequent adjustment, and make such carried forward adjustments, regardless of whether the aggregate adjustment is less than 1%, (a) annually on the anniversary of the first date of issue of the notes and otherwise (b) (1) five business days prior to the maturity of the notes (whether at stated maturity or otherwise) or (2) prior to the repurchase date, unless such adjustment has already been made.

If we adjust the conversion rate pursuant to the above provisions, we will issue a press release through Business Wire or PR Newswire containing the relevant information and make this information available on our website or through another public medium as we may use at that time. Unless and until the trustee shall receive written notice setting forth an adjustment of the conversion rate, the trustee may assume without inquiry that the conversion rate has not been adjusted and that the last conversion rate of which it has knowledge remains in effect.

Notwithstanding the foregoing, any holder of a note shall not have the right to convert the note and will not be able to pay interest on the notes in shares of common stock to the extent that, after giving effect to such conversion or interest payment, such holder (together with the holder’s affiliates) would beneficially own in excess of 4.99% of the number of shares of our common stock outstanding immediately after giving effect to such conversion or interest payment.

We shall not be obligated to issue shares of our common stock upon conversion of the notes and will not be able to pay interest on the notes in shares of common stock to the extent the issuance of such shares of common stock would exceed, in the aggregate, 19.9% of our outstanding common stock on the date of this prospectus supplement (including shares of common stock issued as interest on the notes and upon conversion of the notes), unless we obtain the prior approval of our stockholders (the “Exchange Cap”). We will settle our conversion and interest obligations, if any, in excess of this limitation in cash.

If you elect to convert some or all of your notes at your option prior to June 15, 2018, in addition to the consideration issuable upon conversion you will receive a number of additional shares of our common stock (the “Voluntary Conversion Make Whole Payment”) for the notes being converted or, at our option, cash. The Voluntary Conversion Make Whole Payment will be a number of shares of our common stock or cash equal to the remaining unpaid interest on such portion of such converted notes, up to a maximum of $240.00 per $1,000 principal amount of notes plus any accrued and unpaid interest to such date (“Voluntary Conversion) (collectively, the “Make Whole Payment Amount”). If the Company pays the Make Whole Amount in shares, the shares will be valued at a 7.5% discount to the average VWAP for our common stock for the ten Trading Days ending on and including the Trading Day immediately preceding the date of conversion, subject to the 4.99% and 19.9% limitations described above.

The number of shares of our common stock issuable under the notes depends, in part, on the market price of our shares of common stock. Assuming that all interest payments are made in the form of shares of our common stock, we will issue the following number of shares of our common stock prior to maturity of the notes to pay such interest:

In the event of transactions involving a change of control, we will offer to redeem the notes (including all accrued and unpaid interest thereon) at a price equal to the greater of (i) 110% of the amount being redeemed, (ii) the product of (m) 110% of the amount being redeemed multiplied by (n) the quotient of (A) the highest closing sale price of our common stock during the period beginning on the date immediately before the earlier to occur of (q) the completion of the change of control and (r) the public announcement of the change of control and ending on the trading day immediately before the trading day on which we pay the redemption price divided by (B) the conversion price then in effect immediately before the earlier to occur of (s) the completion of the change of control and (t) the public announcement of the change of control and ending on the trading day immediately before the trading day on which we pay the redemption price, or (iii) the product of (x) 110% of the amount being redeemed multiplied by (y) the quotient of (M) the aggregate cash consideration and the aggregate cash value of any non-cash consideration per share of our common stock to be paid to the holders of the shares of common stock upon the completion of the change of control divided by (N) the conversion price then in effect. If a purchaser of FuelCell does not assume all of the obligations of the notes, you will be obligated to sell, and we will be obligated to buy, the notes at such price.

We are required to notify the trustee promptly upon becoming aware of the occurrence of any default under the indenture known to us. The trustee is then required within 90 calendar days of becoming aware of the occurrence of any default to give to the registered holders of the notes notice of all uncured defaults known to it. However, the trustee may withhold notice to the holders of the notes of any default, except defaults in payment of principal or interest on the notes, if the trustee, in good faith, determines that the withholding of such notice is in the interests of the holders. We are also required to deliver to the trustee, on or before a date not more than 120 calendar days after the end of each fiscal year, a written statement as to compliance with the indenture, including whether or not any default has occurred.

If an event of default specified in the last bullet point listed above occurs and continues with respect to us or any of our significant subsidiaries, the principal amount of the notes and accrued and unpaid interest on the outstanding notes will automatically become due and payable. If any other event of default occurs and is continuing, the trustee or the holders of at least 25% in aggregate principal amount of the outstanding notes may declare the principal amount of the notes and accrued and unpaid interest on the outstanding notes to be due and payable. Thereupon, the trustee may, in its discretion, proceed to protect and enforce the rights of the holders of the notes by appropriate judicial proceedings.

After a declaration of acceleration, but before a judgment or decree for payment of the money due has been obtained by the trustee, the holders of a majority in aggregate principal amount of the notes outstanding, by written notice to us and the trustee, may rescind and annul such declaration if:

The holders of a majority in aggregate principal amount of the outstanding notes will have the right to direct the time, method and place of any proceedings for any remedy available to the trustee, subject to limitations specified in the indenture.

No holder of the notes may pursue any remedy under the indenture, except in the case of a default in the payment of principal or interest (including interest make-whole payments) on the notes, unless:

The holders of a majority in aggregate principal amount of the notes outstanding may, on behalf of the holders of all the notes, waive any past default or event of default under the indenture and its consequences, except:

The indenture (including the terms and conditions of the notes) may not be modified or amended without the written consent or the affirmative vote of each affected holder of a note to:

The indenture (including the terms and conditions of the notes) may be modified or amended, except as described above, with the written consent or affirmative vote of the holders of a majority in aggregate principal amount of the notes then outstanding.

The indenture (including the terms and conditions of the notes) may be modified or amended by us and the trustee, without the consent of the holder of any notes, to, among other things:

The consent of the holders of notes is not necessary under the indenture to approve the particular form of any proposed modification or amendment. It is sufficient if such consent approves the substance of the proposed modification or amendment. After a modification or amendment under the indenture becomes effective, we are required to mail to the holders a notice briefly describing such modification or amendment. However, the failure to give such notice to all the holders, or any defect in the notice, will not impair or affect the validity of the modification or amendment. Any notes held by us or our subsidiaries shall not be entitled to any vote on any matter submitted to the holders of notes.

Any notes held by us or by any person directly or indirectly controlling or controlled by or under direct or indirect common control with us shall be disregarded (from both the numerator and the denominator) for purposes of determining whether the holders of the requisite aggregate principal amount of the outstanding notes have consented to a modification, amendment or waiver of the terms of the indenture, except that for the purposes of determining whether the trustee shall be protected in relying on any such consent, only notes that the trustee knows are so owned shall be so disregarded.

We may, to the extent permitted by law, repurchase any notes in the open market or by tender offer at any price or by private agreement. Any notes repurchased by us may, at our option, be surrendered to the trustee for cancellation, but may not be reissued or resold by us. Any notes surrendered for cancellation may not be reissued or resold and will be promptly cancelled.

Information Concerning the Trustee, Paying Agent, Conversion Agent and Common Stock Transfer Agent and Registrar

We have appointed US Bank National Association, the trustee under the indenture, as paying agent, conversion agent, notes registrar and custodian for the notes. The trustee or its affiliates may also provide other services to us in the ordinary course of their business. The indenture contains certain limitations on the rights of the trustee, if it or any of its affiliates is then our creditor, to obtain payment of claims in certain cases or to realize on certain property received on any claim as security or otherwise. The trustee and its affiliates will be permitted to engage in other transactions with us. However, if the trustee or any affiliate continues to have any conflicting interest and a default occurs with respect to the notes, the trustee must eliminate such conflict or resign.

American Stock Transfer & Trust Company LLC is the transfer agent and registrar for our common stock.

The notes and the indenture shall be governed by, and construed in accordance with, the laws of the State of New York.

Except as otherwise provided herein, we will be responsible for making all calculations called for under the notes. These calculations include, but are not limited to, determinations of the sale price of our common stock, accrued interest payable on the notes and the conversion rate and conversion price. We or our agents will make all these calculations in good faith and, absent manifest error, such calculations will be final and binding on holders of the notes. We will provide a schedule of these calculations to each of the trustee and the conversion agent, and each of the trustee and conversion agent is entitled to rely upon the accuracy of our calculations without independent verification. The trustee will forward these calculations to any holder of the notes upon the request of that holder.

The notes will initially be evidenced by one or more global notes. We will deposit the global notes with DTC and register the global notes in the name of Cede & Co. as DTC’s nominee. Except as set forth below, the global notes may be transferred, in whole or in part, only to another nominee of DTC or to a successor of DTC or its nominee.

Beneficial interests in a global note may be held through organizations that are participants in DTC (called “participants”). Transfers between participants will be affected in the ordinary way in accordance with DTC rules and will be settled in clearing house funds. The laws of some states require that certain persons take physical delivery of securities in definitive form. As a result, the ability to transfer beneficial interests in the global notes to such persons may be limited.

Beneficial interests in a global note held by DTC may be held only through participants, or certain banks, brokers, dealers, trust companies and other parties that clear through or maintain a custodial relationship with a participant, either directly or indirectly (called “indirect participants”). So long as Cede & Co., as the nominee of DTC, is the registered owner of a global note, Cede & Co. for all purposes will be considered the sole holder of such global note. Except as provided below, owners of beneficial interests in a global note will:

We will pay principal of and interest on, and the repurchase price of, the global notes to Cede & Co., as the registered owner of the global notes, by wire transfer of immediately available funds on the maturity date, each interest payment date or the repurchase date, as the case may be. Neither we, the trustee nor any paying agent will be responsible or liable:

DTC has advised us that it will take any action permitted to be taken by a holder of the notes, including the presentation of the notes for conversion, only at the direction of one or more participants in whose account with DTC interests in the global notes are credited, and only in respect of the principal amount of the notes represented by the global notes as to which the participant or participants has or have given such direction.

DTC was created to hold securities for its participants and to facilitate the clearance and settlement of securities transactions between participants through electronic book-entry changes to the accounts of its participants. Participants include securities brokers, dealers, banks, trust companies and clearing corporations and other organizations. Some of the participants or their representatives, together with other entities, own DTC. Indirect access to the DTC system is available to others such as banks, brokers, dealers and trust companies that clear through or maintain a custodial relationship with a participant, either directly or indirectly.

DTC has agreed to the foregoing procedures to facilitate transfers of interests in a global note among participants. However, DTC is under no obligation to perform or continue to perform these procedures, and may discontinue these procedures at any time. We will issue the notes in definitive certificated form if DTC notifies us that it is unwilling or unable to continue as depositary or DTC ceases to be a clearing agency registered under the Exchange Act and a successor depositary is not appointed by us within 90 days. In addition, beneficial interests in a global note may be exchanged for definitive certificated notes upon request by or on behalf of DTC in accordance with customary procedures following the request of a beneficial owner seeking to enforce its rights under such notes or the indenture. The indenture permits us to determine at any time and in our sole discretion that notes shall no longer be represented by global notes. DTC has advised us that, under its current practices, it would notify its participants of our request, but will only withdraw beneficial interests from the global notes at the request of each DTC participant. We would issue definitive certificates in exchange for any such beneficial interests withdrawn.

Neither we, the trustee, registrar, paying agent nor conversion agent will have any responsibility or liability for the performance by DTC or its participants or indirect participants of their respective obligations under the rules and procedures governing their operations.

Under the terms and subject to the conditions in an underwriting agreement dated the date of this prospectus supplement, the underwriters named below, for whom Lazard Capital Markets LLC is acting as representative, have severally agreed to purchase, and we have agreed to sell to them, the aggregate principal amount of notes at the public offering price, less the underwriting discounts and commissions, as set forth on the cover page of this prospectus supplement as indicated below:

The underwriters are offering the notes subject to their acceptance of the notes from us and subject to prior sale. The underwriting agreement provides that the obligations of the underwriters to pay for and accept delivery of the notes offered by this prospectus supplement are subject to the approval of certain legal matters by their counsel, including the absence of any material adverse change in our business and to other conditions. The underwriters are obligated to take and pay for all of the notes offered by this prospectus supplement if any such shares are taken.

The underwriters initially propose to offer the notes directly to the public at the public offering price listed on the cover page of this prospectus supplement. After the initial offering of the notes, the offering price and other selling terms may from time to time be varied by the underwriters.

There is no established public market for the Notes, and we do not intend to apply for a listing of the notes on any securities exchange.

The following table summarizes the public offering price, underwriting discounts and commissions and proceeds before expenses to us:

The expenses of the offering, not including the underwriting discounts and commissions, payable by us are estimated to be $300,000, which includes approximately $125,000 that we have agreed to reimburse the underwriters for legal fees incurred in connection with this offering. The relationship between Lazard Frères & Co. LLC and Lazard Capital Markets LLC is governed by a business alliance agreement between their respective parent companies. Pursuant to such agreement, Lazard Frères & Co. LLC referred this offering to Lazard Capital Markets LLC and will receive a referral fee from Lazard Capital Markets LLC in connection therewith; however, such referral fee is not in addition to the fee paid by us to Lazard Capital Markets LLC described above.

We and the underwriters have agreed to indemnify each other, and we have also agreed to indemnify Lazard Frères & Co. LLC, against certain liabilities, including liabilities under the Securities Act of 1933, as amended, and liabilities arising from breaches of representations and warranties contained in the underwriting agreement. We have also agreed to contribute to payments the underwriters and Lazard Frères & Co. LLC may be required to make in respect of such liabilities

We and each of our executive officers and directors, subject to certain exceptions (including sales by officers and directors to satisfy tax obligations arising from the vesting of restricted stock), have agreed with Lazard Capital Markets LLC not to dispose of or hedge any of our shares of common stock or securities convertible into or exercisable or exchangeable for common stock for 90 days after the date of this prospectus supplement without first obtaining the written consent of Lazard Capital Markets LLC. The 90-day “lock-up” period during which we and our executive officers and directors are restricted from engaging in transactions in our common stock or securities convertible into or exercisable or exchangeable for common stock is subject to extension such that, in the event that either (i) during the last 17 days of the “lock-up” period, we issue an earnings or financial results release or material news or a material event relating to us occurs, or (ii) prior to the expiration of the “lock-up” period, we announce that we will release earnings or financial results during the 16-day period beginning on the last day of the “lock-up” period, then in either case the expiration of the “lock-up” period will be extended until the expiration of the 18-day period beginning on the issuance of the earnings or financial results release or the occurrence of the material news or material event, as applicable, unless Lazard Capital Markets LLC waives, in writing, such an extension.

The notes are convertible for shares of common stock. In order to facilitate the offering of our notes, the underwriters may engage in transactions that stabilize, maintain or otherwise affect the price of our common stock or the notes. Specifically, the underwriters may sell more notes than they are obligated to purchase under the underwriting agreement, creating a short position. The underwriters must close out any short position by purchasing securities in the open market. A short position may be created if the underwriters are concerned that there may be downward pressure on the price of the common stock or the notes in the open market after pricing that could adversely affect investors who purchased notes in this offering. As an additional means of facilitating this offering, the underwriters may bid for, and purchase, shares of our common stock in the open market to stabilize the price of the common stock or the notes. These activities may raise or maintain the market price of our common stock or the notes above independent market levels or prevent or slow a decline in the market price of our common stock or the notes. The underwriters are not required to engage in these activities, may choose not to engage in these activities and may end any of these activities at any time.

A prospectus in electronic format may be made available on websites maintained by the underwriters. The underwriters may agree to allocate a number of shares of common stock to other underwriters for sale to their online brokerage account holders. Internet distributions will be allocated by the underwriters on the same basis as other allocations.

This document is only being distributed to and is only directed at (i) persons who are outside the United Kingdom or (ii) to investment professionals falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005 (the “Order”) or (iii) high net worth entities, and other persons to whom it may lawfully be communicated, falling within Article 49(2)(a) to (e) of the Order (all such persons together being referred to as “relevant persons”). The notes are only available to, and any invitation, offer or agreement to subscribe, purchase or otherwise acquire such notes will be engaged in only with, relevant persons. Any person who is not a relevant person should not act or rely on this document or any of its contents.

(a) it has only communicated or caused to be communicated and will only communicate or cause to be communicated an invitation or inducement to engage in investment activity (within the meaning of Section 21 of the Financial Services and Markets Act 2000 or FSMA) received by it in connection with the issue or sale of the notes in circumstances in which Section 21(1) of the FSMA does not apply to us, and

(b) it has complied with, and will comply with all applicable provisions of FSMA with respect to anything done by it in relation to the shares in, from or otherwise involving the United Kingdom.

To the extent that the offer of the securities offered by this prospectus supplement is made in any Member State of the European Economic Area that has implemented the Prospectus Directive before the date of publication of a prospectus in relation to such securities which has been approved by the competent authority in the Member State in accordance with the Prospectus Directive (or, where appropriate, published in accordance with the Prospectus Directive and notified to the competent authority in the Member State in accordance with the Prospectus Directive), the offer (including any offer pursuant to this document) is only addressed to qualified investors in that Member State within the meaning of the Prospectus Directive or has been or will be made otherwise in circumstances that do not require us to publish a prospectus pursuant to the Prospectus Directive.

In relation to each Member State of the European Economic Area which has implemented the Prospectus Directive (each, a “Relevant Member State”), each underwriter has represented and agreed that with effect from and including the date on which the Prospectus Directive is implemented in that Relevant Member State (the “Relevant Implementation Date”) it has not made and will not make an offer of shares to the public in that Relevant Member State prior to the publication of a prospectus in relation to such securities which has been approved by the competent authority in that Relevant Member State or, where appropriate, approved in another Relevant Member State and notified to the competent authority in that Relevant Member State, all in accordance with the Prospectus Directive, except that it may, with effect from and including the Relevant Implementation Date, make an offer of such securities to the public in that Relevant Member State at any time:

(a) to legal entities which are authorized or regulated to operate in the financial markets or, if not so authorized or regulated, whose corporate purpose is solely to invest in securities,

(b) to any legal entity which has two or more of (1) an average of at least 250 employees during the last financial year; (2) a total balance sheet of more than A43,000,000 and (3) an annual net turnover of more than A50,000,000, as shown in its last annual or consolidated accounts, or

Prospectus Directive. For the purposes of this provision, the S-14 expression an “offer of shares to the public” in relation to any securities in any Relevant Member State means the communication in any form and by any means of sufficient information on the terms of the offer and such securities to be offered so as to enable an investor to decide to purchase or subscribe such securities, as the same may be varied in that Relevant Member State by any measure implementing the Prospectus Directive in that Relevant Member State and the expression “Prospectus Directive” means Directive 2003/71/EC and includes any relevant implementing measure in each Relevant Member State.

The EEA selling restriction is in addition to any other selling restrictions set out below. In relation to each Relevant Member State, each purchaser of securities (other than the underwriters) will be deemed to have represented, acknowledged and agreed that it will not make an offer of the securities offered by this prospectus supplement to the public in any Relevant Member State, except that it may, with effect from and including the date on which the Prospectus Directive is implemented in the Relevant Member State, make an offer of securities to the public in that Relevant Member State at any time in any circumstances which do not require the publication by us of a prospectus pursuant to Article 3 of the Prospectus Directive, provided that such purchaser agrees that it has not and will not make an offer of such securities in reliance or purported reliance on Article 3(2)(b) of the Prospectus Directive. For the purposes of this provision, the expression an “offer of shares to the public” in relation to the securities offered by this prospectus supplement in any Relevant Member State has the same meaning as in the preceding paragraph.

The transfer agent for our common shares to be issued upon conversion of the Notes in this offering is American Stock Transfer & Trust Company. Our common shares are traded on The NASDAQ Global Market under the symbol “FCEL.”

The validity of the securities offered hereby will be passed upon for us by Robinson & Cole LLP, New York, New York. Certain matters will be passed upon for the underwriters by Proskauer Rose LLP, New York, New York.

We are subject to the informational requirements of the Securities Exchange Act of 1934 and, therefore, we file annual, quarterly and current reports, proxy statements and other information with the Securities and Exchange Commission (SEC). Our SEC filings are available to the public over the Internet at the SEC’s website at www.sec.gov. The SEC’s website contains reports, proxy and information statements and other information regarding issuers, such as us, that file electronically with the SEC. You may also read and copy any document we file with the SEC at the SEC’s public Reference Room at 100 F Street, N.E., Room 1580, Washington, D.C. 20549 and the web site of the SEC at www.sec.gov. You may also obtain copies of these documents at prescribed rates by writing to the SEC. Please call the SEC at 1-800-SEC-0330 for further information on the operation of its Public Reference Room. Our common stock is quoted on The Nasdaq Global Market, and you may also inspect and copy our SEC filings at the offices of the National Association of Securities Dealers, Inc. located at 1735 K Street, N.W., Washington, D.C. 20006. The SEC maintains an Internet web site that contains reports, proxy and information statements and other information regarding issuers, including us, that file electronically with the SEC.

You should rely only on the information provided in, and incorporated by reference in, this prospectus supplement and the prospectus and the registration statement. We have not authorized anyone else to provide you with different information. Our securities are not being offered in any state where the offer is not permitted. You should assume that the information in this prospectus supplement is accurate only as of the dates of those documents. Our business, financial condition, results of operations and prospects may have changed since those dates.

The SEC allows us to “incorporate by reference” information that we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this prospectus. Information in this prospectus supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus, while information that we file later with the SEC will automatically update and supersede this information. We incorporate by reference into this registration statement and prospectus the documents listed below, and any future filings we will make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act:

We will furnish without charge to you, on written or oral request, a copy of any or all of the documents incorporated by reference, including exhibits to these documents. You should direct any requests for documents to FuelCell Energy, Inc., Attention: Corporate Secretary, 3 Great Pasture Road, Danbury, Connecticut 06813, telephone: (203) 825-6000.

We have filed with the SEC a registration statement on Form S-3 under the Securities Act with respect to our securities offered hereby. This prospectus supplement, which constitutes a part of the registration statement, does not contain all of the information set forth in the registration statement or the exhibits and schedules filed therewith. We have omitted certain parts of the registration statement as permitted by the rules and regulations of the SEC. For further information about us and our securities offered hereby, reference is made to the registration statement and the exhibits and schedules filed therewith. Statements contained in this prospectus supplement regarding the contents of any contract or any other document that is filed as an exhibit to the registration statement are not necessarily complete, and each such statement is qualified in all respects by reference to the full text of such contract or other document filed as an exhibit to the registration statement.

We may from time to time offer and sell any combination of debt securities, preferred stock, warrants and/or common stock described in this prospectus in one or more offerings. The aggregate initial offering price of all securities sold under this prospectus will not exceed $150,000,000.

The securities may be offered to or through underwriters, through agents or dealers, directly to one or more purchasers or through a combination of such methods. See “Plan of Distribution.”

This prospectus provides a general description of the securities we may offer. Each time we sell securities, we will provide specific terms of the securities offered in a supplement to this prospectus. The prospectus supplement may also add, update or change information contained in this prospectus. You should read this prospectus and the applicable prospectus supplement carefully before you invest in any securities. This prospectus may not be used to consummate a sale of securities unless accompanied by the applicable prospectus supplement.

We will use the net proceeds received from the sale of the securities by the Company for general corporate purposes.

Our common stock is quoted on the Nasdaq Global Market under the symbol “FCEL”. No public market currently exists for the other securities offered hereby. The applicable prospectus supplement will contain information, where applicable, as to any other listing on any securities exchange of the securities covered by the prospectus supplement.

Our principal executive offices are located at 3 Great Pasture Road, Danbury, Connecticut 06813, and our telephone number is (203) 825-6000.

Investing in our securities involves risks that are described in the “Risk Factors” section beginning on page 5 of this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

When used in this prospectus, the words “expects”, “anticipates”, “estimates”, “should”, “will”, “could”, “would”, “may”, and similar expressions are intended to identify forward-looking statements. Such statements relate to the development and commercialization of FuelCell Energy, Inc’s. and its subsidiaries (“FuelCell Energy”, “Company”, “we”, “us” and “our”) fuel cell technology and products, future funding under government research and development contracts, the expected cost competitiveness of our technology, and our ability to achieve our sales plans and cost reduction targets. These and other forward-looking statements contained in this prospectus are subject to risks and uncertainties, known and unknown, that could cause actual results to differ materially from those forward-looking statements, including, without limitation, general risks associated with product development and manufacturing, changes in the utility regulatory environment, potential volatility of energy prices, government appropriations, the ability of the government to terminate its development contracts at any time, rapid technological change, and competition and changes in accounting policies or practices adopted voluntarily or as required by accounting principles generally accepted in the United States, as well as other risks contained under Item 7 “Management’s Discussion and Analysis of Financial Condition and Results of Operations — Factors That May Affect Future Results” of our Annual Report on Form 10-K for the year ended October 31, 2009. We cannot assure you that we will be able to meet any of our development or commercialization schedules, that the government will appropriate the funds anticipated by us under our government contracts, that the government will not exercise its right to terminate any or all of our government contracts, that any of our products or technology, once developed, will be commercially successful, or that we will be able to achieve any other result anticipated in any other forward-looking statement contained herein. The forward-looking statements contained herein speak only as of the date of this prospectus. Except for ongoing obligations to disclose material information under the federal securities laws, we expressly disclaim any obligation or undertaking to release publicly any updates or revisions to any such statement to reflect any change in our expectations or any change in events, conditions or circumstances on which any such statement is based.

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission (“SEC”) utilizing a “shelf” registration process. Under this shelf registration process, we may sell any combination of the securities described in this prospectus in one or more offerings up to a total dollar amount of $150,000,000. This prospectus provides you with a general description of the securities that we may offer. Each time we sell securities under this shelf registration, we will provide a prospectus supplement that will contain specific information about the terms of the offering. The prospectus supplement may also add, update or change information contained in this prospectus. If there is any inconsistency between the information in this prospectus and any prospectus supplement, you should rely on the information in that prospectus supplement. You should carefully read both this prospectus and any prospectus supplement, including documents incorporated by reference herein, together with the additional information described in the section entitled “Where You Can Find More Information.”

We have not authorized any dealer, salesman or other person to give any information or to make any representation other than those contained or incorporated by reference in this prospectus and the accompanying supplement to this prospectus. You must not rely upon any information or representation not contained or incorporated by reference in this prospectus or the accompanying prospectus supplement. This prospectus and the accompanying supplement to this prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus and the accompanying supplement to this prospectus constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction. You should not assume that the information contained in this prospectus and the accompanying prospectus supplement is accurate on any date subsequent to the date set forth on the front of the document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus and any accompanying prospectus supplement is delivered or securities sold on a later date.

FuelCell Energy, Inc. (“FuelCell Energy”, “Company”, “we” or “us”) is a world leader in the development and production of stationary fuel cells for commercial, industrial, government and utility customers. Our ultra-clean, high efficiency Direct FuelCell^® power plants are generating power at over 50 locations worldwide. Our products have generated over 550 million kWh of power using a variety of fuels including renewable wastewater gas, food and beverage waste, natural gas and other hydrocarbon fuels.

Our Company was founded in Connecticut in 1969 and reincorporated in Delaware in 1999. Our core fuel cell products (“Direct FuelCell^®” or “DFC^® Power Plants”) offer higher efficiency stationary power generation for customers. In addition to our commercial products, we continue to develop our carbonate fuel cells, planar solid oxide fuel cell (“SOFC”) technology and other fuel cell technology with our own and government research and development funds.

Our proprietary carbonate DFC Power Plants electrochemically (without combustion) produce electricity directly from readily available hydrocarbon fuels such as natural gas and biogas. Customers buy fuel cells to reduce cost and pollution, and improve power reliability. Electric generation without combustion significantly reduces harmful pollutants such as NOX, SOX and particulates. Higher fuel efficiency results in lower emissions of carbon dioxide (“CO₂”), a major greenhouse gas, and also results in less fuel needed per kWh of electricity generated and Btu of heat produced. Greater efficiency reduces customers’ exposure to volatile fuel costs and minimizes operating costs. Our fuel cells operate 24/7 providing reliable power to both on-site customers and for grid-support applications.

Compared to other power generation technologies, our products offer significant advantages including:

Typical customers for our products include manufacturers, mission critical institutions such as correction facilities and government installations, hotels, natural gas letdown stations and customers who can use renewable gas for fuel such as breweries, food processors, and wastewater treatment facilities. Our MW-class products are also used to supplement the grid for utility customers. With increasing demand for renewable and ultra-clean power options and increased volatility in electric markets, our customers gain control of power generation economics, reliability, and emissions.

Our DFC Power Plants are protected by 62 U.S. and 67 international patents. We currently have 33 U.S. and 171 international patents under application.

As used in this prospectus, all degrees refer to Fahrenheit (oF), and kilowatt and megawatt numbers designate nominal or rated capacity of the referenced power plant. As used in this prospectus, “kilowatt” (kW) means 1,000 watts; “megawatt” (MW) means 1,000,000 watts; and “kilowatt hour” (kWh) is equal to 1 kW of power supplied to or taken from an electric circuit steadily for one hour. All dollar amounts are in U.S. dollars unless otherwise noted.

Investing in our common stock involves a high degree of risk. The risks and uncertainties described below are not the only ones facing us. Additional risks and uncertainties that we are unaware of, or that we currently deem immaterial, also may become important factors that affect us. Before purchasing our securities, you should carefully consider the following risk factors, as well as all other information contained in this prospectus and incorporated by reference, including our consolidated financial statements and the related notes. If any of the following risks actually occur, our business, financial condition, or results of operations could be materially and adversely affected. In such cases, the trading price of our securities could decline, and you may lose all or part of your investment.

We have incurred losses and anticipate continued losses and negative cash flow.

We have been transitioning from a contract research and development company to a commercial products developer and manufacturer. As such, we have not been profitable since our fiscal year ended October 31, 1997. We expect to continue to incur net losses and generate negative cash flow until we can produce sufficient revenues to cover our costs. We may never become profitable. Even if we do achieve profitability, we may be unable to sustain or increase our profitability in the future. For the reasons discussed in more detail below, there are substantial uncertainties associated with our achieving and sustaining profitability. We have, from time to time, sought financing in the public markets in order to fund operations. Our future ability to obtain such financing, if required, could be impaired by a variety of factors, including the price of our common stock, the current global economic crisis and general market conditions.

Our cost reduction strategy may not succeed or may be significantly delayed, which may result in our inability to offer our products at competitive prices and may adversely affect our sales.

Our cost reduction strategy is based on the assumption that a significant increase in production will result in economies of scale. In addition, our cost reduction strategy relies on advancements in our manufacturing process, global competitive sourcing, engineering design and technology improvements (including stack life and projected power output). Failure to achieve our cost reduction targets would have a material adverse effect on our commercialization plans and, therefore, our business prospects, results of operations and financial condition.

Our products compete with products using other energy sources, and if the prices of the alternative sources are lower than energy sources used by our products, sales of our products will be adversely affected. Volatility of electricity prices may impact sales of our products in the markets in which we compete.

Our DFC Power Plants operate using a variety of hydrocarbon fuels, including natural gas, methanol, diesel, biogas, coal gas, coal mine methane, and propane. If these fuels are not readily available or if their prices increase such that electricity produced by our products costs more than electricity provided by other generation sources, our products would be less economically attractive to potential customers. In addition, we have no control over the prices of several types of competitive energy sources such as oil, gas or coal as well as local utility electricity costs. Significant decreases (or short term increases) in the price of these fuels or grid delivered prices for electricity could also have a material adverse effect on our business because other generation sources could be more economically attractive to consumers than our products.

The reduction or elimination of government subsidies and economic incentives for alternative energy technologies, including our fuel cell power plants, could reduce demand for our products, lead to a reduction in our revenues and adversely impact our operating results.

portfolio standards programs). Many of these government incentives expire, phase out over time, exhaust the allocated funding, or require renewal by the applicable authority. In addition, these incentive programs could be challenged by utility companies, found to be unconstitutional, and/or could be reduced or discontinued for other reasons. The reduction, elimination, or expiration of government subsidies and economic incentives may result in the diminished economic competitiveness of our power plants to our customers and could materially and adversely affect the growth of alternative energy technologies, including our fuel cells, as well as our future operating results.

Financial markets worldwide have been impacted by a credit crisis which may have a material adverse impact on our Company, our customers and our suppliers.

Financial markets have been impacted by a credit crisis worldwide, affecting both debt and equity markets. This has substantially limited the amount of financing available to all companies, including companies with substantially greater resources, better credit ratings and more successful operating histories than ours. It is impossible to predict how long this crisis will last or how it will be resolved and it may have a materially adverse affect on us for a number of reasons, such as:

If we, or our customers and suppliers, cannot obtain financing under favorable terms during the current financial crisis or should the financial crisis worsen, our business may be negatively impacted.

We have signed product sales contracts, long-term service agreements and power purchase agreements with customers. Revenues earned are subject to accounting estimates and technology and operating risks as well as market conditions that may affect our operating results.

Revenue from sales of our power plants and modules are recognized under the percentage of completion method of accounting. Revenues are recognized proportionally as costs are incurred and assigned to a customer contract by comparing total expected costs for each contract to the total contract value. Prior to fiscal 2010, we did not provide for a contract loss reserve on product sales contracts as products were in their early stages of development and market acceptance, and the total costs to produce, install and commission these units could not be reasonably estimated. As a result of a consistent production rate over the past two fiscal years and installation and commissioning experience for our major product lines, management now believes that it has sufficient product cost history to reasonably estimate the total costs of our fuel cell product sales contracts. Accordingly, effective November 1, 2009, a contract loss reserve on product sales contracts is recognized at the time we become aware that estimated total costs are expected to exceed the contract sales price. Actual results could vary from initial estimates and reserve estimates will be updated as we gain further manufacturing and operating experience. For component and spare parts sales, revenue is recognized upon shipment under the terms of the customer contract.

Revenue earned by performing routine monitoring and maintenance under long term service agreements (“LTSAs”) is recognized ratably over the term of the contract. Costs for performing maintenance are recognized as incurred. For service contracts that include a minimum operating output over the course of the contract, a portion of the contract revenue is deferred until such time as it is earned through power plant performance.

Under the terms of our power purchase agreements (“PPAs”), customers agree to purchase power from our fuel cell power plants at negotiated rates, generally for periods of five to ten years. Electricity rates are generally a function of the customer’s current and future electricity pricing available from the grid. Revenues are earned and collected under these PPAs as power is produced. As owner of the power plants in these PPA entities, we are responsible for all operating costs necessary to maintain, monitor and repair the power plants. Under certain agreements, we are also responsible for procuring fuel, generally natural gas, to run the power plants. Should electricity rates decrease or operating costs increase from our original estimates, our results of operations could be negatively impacted. We have qualified for incentive funding for these projects in California under the state’s SGIP and from other government programs. Funds are payable upon commercial installation and demonstration of the plant and may require return of the funds for failure of certain performance requirements. Revenue related to these incentive funds is recognized ratably over the performance period. We are not required to produce minimum amounts of power under our PPA agreements and we have the right to terminate PPA agreements by giving written notice to the customer, subject to certain exit costs.

We extend product warranties and enter into long-term service agreements which are subject to accounting estimates. Future technology and operating risks as may affect our operating results.

We warranty our products for a specific period of time against manufacturing or performance defects. Our warranty is limited to a term of generally 15 months after shipment or 12 months after installation of our products. We reserve for estimated future warranty costs based on historical experience. Given our limited operating experience, particularly for newer product designs, actual results could vary from initial estimates. Estimates used to record warranty reserves are updated as we gain further operating experience.

In addition to the standard product warranty, we have entered into LTSAs with certain customers to provide monitoring, maintenance and repair services for fuel cell power plants ranging from one to 13 years. Our standard service agreement term is five years. Under the terms of our LTSAs, the power plant must meet a minimum operating output during the term. If minimum output falls below the contract requirement, we may replace the customer’s fuel cell stack with a new or used unit. Our contractual liability under LTSAs is limited to the amount of service fees payable under the contract. This can often times be less than the cost of a new stack replacement. In order to continue to meet customer expectations on early product designs, at our election we have often incurred costs in excess of our contractual liabilities.

While we currently expect that LTSA’s for power plants that have our newer five-year stack design should not require a stack change to continue to meet minimum operating levels during the initial five-year term of the contract, we have limited operating experience with these products. The Company will continue to monitor performance and life of these stacks based on actual performance at customer sites. Stack replacements for new agreements which include the five-year stack design are expected to only be required upon renewal of the service agreement. Accordingly, five-year LTSAs with our five-year stack design have not required a contract loss reserve. We expect the replacement of older stacks produced prior to the five-year stack design to continue over the next several years, and, as a result, we may continue to incur losses in order to maintain power plants to the extent costs exceed our contract loss reserves on these legacy service agreements. Future costs for maintaining legacy service agreements will be determined by a number of factors, including the estimated life of the stack, used replacement stacks available, our limit of liability on service agreements and future operating plans for the power plant. If our expectations are incorrect for our five-year stack design, we could incur significant warranty, support and repair costs, could divert the attention of our engineering personnel from our product development efforts, and could harm our relationships with our customers.

Our products are complex and could contain defects which could reduce sales of our products or result in claims against us.

We develop complex and evolving products. Despite testing by us, our customers and our suppliers, issues may be found in existing or new products. This could result in a delay in recognition or loss of revenues, loss of market share or failure to achieve market acceptance. The occurrence of defects could also cause us to incur significant warranty, support and repair costs, could divert the attention of our engineering personnel from our product development efforts, and could harm our relationships with our customers. The occurrence of these problems could result in the delay or loss of market acceptance of our products and would likely harm our business. Defects or performance problems with our products could result in financial or other damages to our customers. Our customers could also seek and obtain damages from us for their losses. From time to time, we have been involved in disputes regarding product warranty issues. Although we seek to limit our liability, a product liability claim brought against us, even if unsuccessful, would likely be time consuming and could be costly to defend.

We compete on the basis of our products’ reliability, fuel efficiency, environmental considerations and cost. Technological advances in alternative energy products or improvements in the electric grid or other sources of power generation, or other fuel cell technologies may negatively affect the development or sale of some or all of our products or make our products non-competitive or obsolete prior to commercialization or afterwards. Other companies, some of which have substantially greater resources than ours, are currently

engaged in the development of products and technologies that are similar to, or may be competitive with, our products and technologies.

Several companies in the U.S. are involved in fuel cell development, although we believe we are the only domestic company engaged in significant manufacturing and commercialization of carbonate fuel cells. Emerging fuel cell technologies (and companies developing them) include proton exchange membrane fuel cells (Ballard Power Systems, Inc.; United Technologies Corp. or UTC Power; and Plug Power), phosphoric acid fuel cells (UTC Power and Samsung Everland) and solid oxide fuel cells (Siemens Westinghouse Electric Company, General Electric, Delphi, Rolls Royce, Bloom Energy, and Acumentrics). Each of these competitors has the potential to capture market share in our target markets.

There are other potential carbonate fuel cell competitors internationally. In Europe, a company in Italy, Ansaldo Fuel Cells, is actively engaged in carbonate fuel cell development and is a potential competitor. Fuji Electric has been involved with both PEM and phosphoric acid fuel cells. In Korea, Doosan Corporation is engaged in carbonate fuel cell development.

Other than fuel cell developers, we must also compete with such companies as Caterpillar, Cummins, Wartsilla, MTU, Mitsubishi Heavy Industries and Detroit Diesel, which manufacture more mature combustion-based equipment, including various engines and turbines, and have well-established manufacturing, distribution, and operating and cost features. Electrical efficiency of these products can be competitive with our DFC Power Plants in certain applications. Significant competition may also come from gas turbine companies like General Electric, Ingersoll Rand, Solar Turbines and Kawasaki, which have recently made progress in improving fuel efficiency and reducing pollution in large-size combined cycle natural gas fueled generators. These companies have also made efforts to extend these advantages to smaller sizes.

We have a large and influential stockholder, which may make it difficult for a third party to acquire our common stock.

POSCO Power (“POSCO”) owns, as of July 31, 2010, approximately 10 percent of our outstanding common stock, which could make it difficult for a third party to acquire our common stock. POSCO is also a licensee of our technology and purchaser of our products. Therefore, it may be in POSCO’s interest to possess substantial influence over matters concerning our overall strategy and technological and commercial development.

We have limited experience manufacturing our products on a commercial basis. Our overall manufacturing process has a production capacity of 70 MW per year. We expect that we will further increase our manufacturing capacity based on market demand. We cannot be sure that we will be able to achieve any planned increases in production capacity. Also, as we scale up our production capacity, we cannot be sure that unplanned failures or other technical problems relating to the manufacturing process will not occur.

Even if we are successful in achieving our planned increases in production capacity, we cannot be sure that we will do so in time to meet our product commercialization schedule or to satisfy the requirements of our customers. Additionally, we cannot be sure that we will be able to develop efficient, low-cost manufacturing capabilities and processes (including automation) that will enable us to meet our cost goals and profitability projections. Our failure to develop advanced manufacturing capabilities and processes, or meet our cost goals, could have a material adverse effect on our business prospects, results of operations and financial condition.

Unanticipated increases or decreases in business growth may result in adverse financial consequences for us.

in part, represent excess capacity for which we may not recover the cost; in that circumstance, our revenues may be inadequate to support our committed costs and our planned growth, and our gross margins, and business strategy would be adversely affected.

As we continue to commercialize our products, we intend to continue to develop warranties, power production guarantees and other terms and conditions relating to our products that will be acceptable to the marketplace, and continue to develop a service organization that will aid in servicing our products and obtain self-regulatory certifications, if available, with respect to our products. Failure to achieve any of these objectives may also slow the development of a sufficient market for our products and, therefore, have a material adverse effect on our results of operations and financial condition.

We are substantially dependent on a small number of customers and the loss of any one of these customers could adversely affect our business, financial condition and results of operations.

We contract with a small number of customers for the sale of our products and for research and development contracts. For the nine months ended July 31, 2010 our top three customers (Posco Power, Pacific Gas and Electric Company and the U.S. Department of Energy and other governmental agencies) accounted for 84 percent of our total annual consolidated revenue. For the fiscal years ended October 31, 2009, 2008 and 2007, our top two customers, POSCO Power and the U.S. Department of Energy and other governmental agencies, accounted for 80 percent, 62 percent and 45 percent, respectively of our total annual consolidated revenue. Our largest strategic partner, POSCO Power, accounted for 64 percent, 46 percent and 13 percent of total revenues, and the DOE and other governmental agencies accounted for 16 percent, 17 percent and 31 percent of total revenues for the fiscal years ended October 31, 2009, 2008 and 2007, respectively.

There can be no assurance that we will continue to achieve historical levels of sales of our products to our largest customers. Even though our customer base is expected to increase and our revenue streams to diversify, a substantial portion of net revenues could continue to depend on sales to a limited number of customers. Our agreements with these customers may be cancelled if we fail to meet certain product specifications or materially breach the agreement, and our customers may seek to renegotiate the terms of current agreements or renewals. The loss of, or a reduction in sales to, one or more of our larger customers could have a material adverse affect on our business, financial condition and results of operations.

Our government research and development contracts are subject to the risk of termination by the contracting party and we may not realize the full amounts allocated under the contracts due to the lack of Congressional appropriations.

A portion of our fuel cell revenues have been derived from long-term cooperative agreements and other contracts with the U.S. Department of Energy, the U.S. Department of Defense, the U.S. Navy, and other U.S. government agencies. These agreements are important to the continued development of our technology and our products.

Generally, our U.S. government research and development contracts are subject to the risk of termination at the convenience of the contracting agency. Furthermore, these contracts, irrespective of the amounts allocated by the contracting agency, are subject to annual Congressional appropriations and the results of government or agency sponsored reviews and audits of our cost reduction projections and efforts. We can only receive funds under these contracts ultimately made available to us annually by Congress as a result of the appropriations process. Accordingly, we cannot be sure whether we will receive the full amounts awarded under our government research and development or other contracts. Failure to receive the full amounts under any of our government research and development contracts could materially and adversely affect our business prospects, results of operations and financial condition.

A negative government audit could result in an adverse adjustment of our revenue and costs and could result in civil and criminal penalties.

The U.S. government has certain rights relating to our intellectual property, including restricting or taking title to certain patents.

Eleven U.S. patents that we own have resulted from government-funded research and are subject to the risk of exercise of “march-in” rights by the government. March-in rights refer to the right of the U.S. government or a government agency to exercise its non-exclusive, royalty-free, irrevocable worldwide license to any technology developed under contracts funded by the government if the contractor fails to continue to develop the technology. These “march-in” rights permit the U.S. government to take title to these patents and license the patented technology to third parties if the contractor fails to utilize the patents. In addition, our DOE-funded research and development agreements also require us to agree that we will not provide to a foreign entity any fuel cell technology subject to that agreement unless the fuel cell technology will be substantially manufactured in the U.S. Accordingly, we could lose some or all of the value of these patents.

A failure to qualify as a “small business” could adversely affect our rights to own future patents under DOE-funded contracts.

Qualifying as a “small business” under DOE contracts allows us to own the patents that we develop under DOE contracts. A “small business” under applicable government regulations generally consists of no more than 500 employees averaged over a one year period. If we continue to grow, we will no longer qualify as a “small business” and no longer own future patents we develop under future contracts, grants or cooperative agreements funded by the DOE based on such certification, unless we obtain a patent waiver from the DOE. Should we not obtain a patent waiver and outright ownership, we would nevertheless retain exclusive rights to any such patents, so long as we continue to commercialize the technology covered by the patents. As of July 31, 2010, we had a total of 449 full-time employees; however, we cannot assure you that we will continue to qualify as a “small business” in the future.

We cannot assure you that we will enter into distributor relationships that are consistent with, or sufficient to support, our commercialization plans, and our growth strategy or that these relationships will be on terms favorable to us. Even if we enter into these types of relationships, we cannot assure you that the distributors with which we form relationships will focus adequate resources on selling our products or will be successful in selling them. Some of these distributor arrangements have or will require that we grant exclusive distribution rights to companies in defined territories. These exclusive arrangements could result in our being unable to enter into other arrangements at a time when the distributor with which we form a relationship is not successful in selling our products or has reduced its commitment to marketing our products. In addition, certain distributor arrangements include, and some future distributor arrangements may also include, the issuance of equity and warrants to purchase our equity, which may have an adverse affect on our stock price. To the extent we enter into distributor relationships, the failure of these distributors to assist us with the marketing and distribution of our products may adversely affect our results of operations and financial condition.

We cannot be sure that our original equipment manufacturers (“OEMs”) will manufacture or package products using our Direct FuelCell components. Our success will largely depend upon our ability to make our products compatible with the power plant products of OEMs and the ability of these OEMs to sell their products containing our products. In addition, some OEMs may need to redesign or modify their existing power plant products to fully incorporate our products. Accordingly, any integration, design, manufacturing or marketing problems encountered by OEMs could adversely affect the market for our products and, therefore, our business prospects, results of operations and financial condition.

We depend on third party suppliers for the development and supply of key raw materials and components for our products.

We use various raw materials and components to construct a fuel cell module, including nickel and stainless steel which are critical to our manufacturing process. We also rely on third-party suppliers for the balance-of-plant components in our products. Suppliers must undergo a qualification process, which takes four to twelve months. We continually evaluate new suppliers and we are currently qualifying several new suppliers. There are a limited number of suppliers for some of the key components of products. A supplier’s failure to develop and supply components in a timely manner, supply components that meet our quality, quantity or cost requirements and technical specifications, or our inability to obtain alternative sources of these components on a timely basis or on terms acceptable to us, could harm our ability to manufacture our Direct FuelCell products. In addition, to the extent the processes that our suppliers use to manufacture components are proprietary; we may be unable to obtain comparable components from alternative suppliers.

We do not know when or whether we will secure long-term supply relationships with any of our suppliers or whether such relationships will be on terms that will allow us to achieve our objectives. Our business prospects, results of operations and financial condition could be harmed if we fail to secure long-term relationships with entities that will supply the required components for our Direct FuelCell products.

We depend on our intellectual property, and our failure to protect that intellectual property could adversely affect our future growth and success.

Failure to protect our existing intellectual property rights may result in the loss of our exclusivity or the right to use our technologies. If we do not adequately ensure our freedom to use certain technology, we may have to pay others for rights to use their intellectual property, pay damages for infringement or misappropriation, or be enjoined from using such intellectual property. We rely on patent, trade secret, trademark and copyright law to protect our intellectual property. As of July 31, 2010, we had 62 current U.S. patents and 67 international patents covering our fuel cell technology. These patents will expire between 2010 and 2028 and have an average remaining life of 11 years.

Our future success will depend on our ability to attract and retain qualified management and technical personnel.

Our future success is substantially dependent on the continued services and performance of our executive officers and other key management, engineering, scientific, manufacturing and operating personnel, particularly R. Daniel Brdar, our Chief Executive Officer and Chairman of the Board of Directors. The loss of the services of any executive officer, including Mr. Brdar, or other key management, engineering, scientific, manufacturing

and operating personnel, could materially adversely affect our business. Our ability to achieve our development and commercialization plans will also depend on our ability to attract and retain additional qualified management and technical personnel. Recruiting personnel for the fuel cell industry is competitive. We do not know whether we will be able to attract or retain additional qualified management and technical personnel. Our inability to attract and retain additional qualified management and technical personnel, or the departure of key employees, could materially and adversely affect our development and commercialization plans and, therefore, our business prospects, results of operations and financial condition.

Utility companies could impose customer fees or interconnection requirements on our customers that could make our products less desirable.

Several states have created and adopted, or are in the process of creating, their own interconnection regulations covering both technical and financial requirements for interconnection to utility grids. Depending on the complexities of the requirements, installation of our systems may become burdened with additional costs that might have a negative impact on our ability to sell systems. The Institute of Electrical and Electronics Engineers has been working to create an interconnection standard addressing the technical requirements for distributed generation to interconnect to utility grids. Many parties are hopeful that this standard will be adopted nationally to help reduce the barriers to deployment of distributed generation such as fuel cells; however this standard may not be adopted nationally thereby limiting the commercial prospects and profitability of our fuel cell systems.

We could be liable for environmental damages resulting from our research, development or manufacturing operations.

in settling environmental damage claims, and in some instances, we may not be reimbursed at all. Our business is subject to numerous federal, state, and local laws and regulations that govern environmental protection and human health and safety. We believe that our businesses are operating in compliance in all material respects with applicable environmental laws, however these laws and regulations have changed frequently in the past and it is reasonable to expect additional and more stringent changes in the future.

Our products use inherently dangerous, flammable fuels, operate at high temperatures and use corrosive carbonate material, each of which could subject our business to product liability claims.

Our business exposes us to potential product liability claims that are inherent in products that use hydrogen. Our products utilize fuels such as natural gas and convert these fuels internally to hydrogen that is used by our products to generate electricity. The fuels we use are combustible and may be toxic. In addition, our Direct FuelCell products operate at high temperatures and use corrosive carbonate material, which could expose us to potential liability claims. Although we have comprehensive safety, maintenance, and training programs in place and follow third-party certification protocols, codes and standards, we cannot guarantee there will not be accidents. Any accidents involving our products or other hydrogen-using products could materially impede widespread market acceptance and demand for our products. In addition, we might be held responsible for damages beyond the scope of our insurance coverage. We also cannot predict whether we will be able to maintain adequate insurance coverage on acceptable terms.

Since we market our products both inside and outside the U.S., our success depends in part, on our ability to secure international customers and our ability to manufacture products that meet foreign regulatory and commercial requirements in target markets. Sales to customers located outside the U.S. accounted for 65 percent, 50 percent and 34 percent of our consolidated revenue in fiscal 2009, 2008 and 2007, respectively. Sales to customers in Asia represent the majority of our international sales. We have limited experience developing and manufacturing our products to comply with the commercial and legal requirements of international markets. In addition, we are subject to tariff regulations and requirements for export licenses, particularly with respect to the export of some of our technologies. We face numerous challenges in our international expansion, including war, insurrection, civil unrest, strikes and other political risks, renegotiation of contracts with governmental entities, unexpected changes in regulatory requirements, fluctuations in currency restrictions and exchange rates, longer accounts receivable requirements and collections, difficulties in managing international operations, potentially adverse tax consequences, restrictions on repatriation of earnings and the burdens of complying with a wide variety of international laws. Our international operations may also be adversely affected by laws and policies of the United States affecting foreign policy, foreign trade, taxation and the possible inability to subject foreign persons to the jurisdiction of the courts in the United States. Any of these factors could adversely affect our results of operations and financial condition.

Potential Regulations regarding climate change could alter the way we conduct our business.

Governments around the world are beginning to address climate change matters. This may result in new environmental regulations that may unfavorably impact us, our suppliers and our customers. The cost of meeting these requirements may have an adverse impact on our financial condition, results of operations and cash flows.

We depend on relationships with strategic partners, and the terms and enforceability of many of these relationships are not certain.

We have entered into relationships with strategic partners for design, product development and distribution of our existing products and products under development, some of which may not have been documented by a definitive agreement. The terms and conditions of many of these agreements allow for termination by the partners. Termination of any of these agreements could adversely affect our ability to design, develop and distribute these products to the marketplace. We cannot assure you that we will be able to successfully negotiate and execute definitive agreements with any of these partners, and failure to do so may effectively terminate the relevant relationship.

Provisions of Delaware and Connecticut law and of our charter and by-laws may make a takeover more difficult.

The rights of the Series 1 preferred shares and Series B preferred stock could negatively impact FuelCell and our Stockholders.

The terms of the Series 1 preferred shares issued by FuelCell Energy, Ltd. (“FCE”), our wholly-owned, indirect subsidiary, provide rights to the holder, Enbridge, which could negatively impact us. Quarterly dividends of Cdn.$312,500 accrue on the Series 1 preferred shares (subject to possible reduction pursuant to the terms of the Series 1 preferred shares). We have agreed to pay a minimum of Cdn.$500,000 in cash or

common stock annually to Enbridge, as long as Enbridge holds these shares. Interest accrues on cumulative unpaid dividends at an annual rate of 9 percent, compounded quarterly. All cumulative unpaid dividends must be paid by December 31, 2010. Dividend and accrued interest payments can be made in cash or common stock at the option of the FCE, and such shares issued may be unregistered. Using an exchange rate of Cdn.$0.9592 to U.S.$1.00 (exchange rate on September 9, 2010), cumulative unpaid dividends and accrued interest on the Series 1 Preferred Shares was $10.6 million as of September 9, 2010. Subsequent to 2010, FCE will be required to pay an annual dividend of Cdn.$1.25 million so long as the Series 1 Preferred Shares remain outstanding. We have guaranteed FCE’s dividend obligations under the Series 1 preferred shares.

We are also required to issue common stock to the holder of the Series 1 preferred shares if and when the holder exercises its conversion rights. The number of shares of common stock that we may issue upon conversion could be significant and dilutive to our existing stockholders. For example, assuming the holder of the Series 1 preferred shares exercises its conversion rights after July 31, 2020 and assuming our common stock price is $1.11 (our common stock closing price on September 9, 2010) and an exchange rate of Cdn.$0.9592 to U.S.$1.00 (exchange rate on September 9, 2010) at the time of conversion, we would be required to issue approximately 23,730,507 shares of our common stock.

Our results of operations could vary as a result of methods, estimates and judgments we use in applying our accounting policies.

The methods, estimates and judgments we use in applying our accounting policies have a significant impact on our results of operations (see “Critical Accounting Policies and Estimates” in Part II, Item 7 of our Annual Report on Form 10-K for the year ended October 31, 2009 and Note 1 of Notes to Consolidated Financial Statements of our Form 10-Q for the nine months ended July 31, 2010). Such methods, estimates and judgments are, by their nature, subject to substantial risks, uncertainties and assumptions, and factors may arise over time that could lead us to reevaluate our methods, estimates and judgments.

As we gain experience in future periods, management will continue to reevaluate its estimates for contract losses, warranty and inventory reserves. Changes in those estimates and judgments could significantly affect our results of operations and financial condition. We may also adopt changes required by the Financial Accounting Standards Board and the Securities and Exchange Commission.

Management will have broad discretion as to the use of the proceeds of this offering.

We have not designated the amount of net proceeds we will receive from this offering for any particular purpose. Accordingly, our management will have broad discretion as to the application of these net proceeds and could use them for purposes other than those contemplated at the time of this offering. Our stockholders may not agree with the manner in which our management chooses to allocate and spend the net proceeds.

Future sales of substantial amounts of our common stock could affect the market price of our common stock.

Future sales of substantial amounts of our common stock, or securities convertible or exchangeable into shares of our common stock, into the public market, including shares of our common stock issued upon exercise of options and warrants, or perceptions that those sales could occur, could adversely affect the prevailing market price of our common stock and our ability to raise capital in the future.

The ratio of our earnings to fixed charges are set forth below for each of the periods indicated.

Except as may be provided in an applicable prospectus supplement, we will use the net proceeds from the sale of the debt securities, preferred stock, warrants and/or common stock for market and product development, project financing and general corporate purposes. General corporate purposes may include capital expenditures, repayment of debt, payment of dividends and any other purposes that we may specify in any prospectus supplement. We may invest the net proceeds temporarily until we use them for their stated purpose.

We may from time to time offer and sell debt securities consisting of debentures, notes and/or other unsecured evidences of indebtedness (the “Debt Securities”). The following description of Debt Securities will apply to the Debt Securities offered by this prospectus unless we provide otherwise in the applicable prospectus supplement. The applicable prospectus supplement for a

The Debt Securities will be either our unsecured senior debt securities (the “Senior Debt Securities”) or our unsecured subordinated debt securities (the “Subordinated Debt Securities”). The Senior Debt Securities may be issued under an Indenture (the “Senior Indenture”) between us and a trustee that will be identified in a prospectus supplement (the “Senior Trustee”). The Senior Debt Securities will be our direct, unsecured obligations and will rank equally with all of our outstanding unsecured senior indebtedness. The Subordinated Debt Securities may be issued under a second indenture (the “Subordinated Indenture”) between us and a trustee that will be identified in a prospectus supplement (the “Subordinated Trustee”), which may be the same as the Senior Trustee. The Subordinated Debt Securities will be our direct, unsecured obligations and, unless otherwise specified in the prospectus supplement relating to a particular series of Subordinated Debt Securities offered by such prospectus supplement, will be subject to the subordination provisions set forth under the heading “Subordination of the Subordinated Debt Securities” below. The Senior Indenture and the Subordinated Indenture are together called the “Indentures” and the Senior Trustee and the Subordinated Trustee are together called the “Trustee.”

The following summary of certain provisions of the Indentures is not complete. You should refer to the form of each Indenture, copies of which will be filed as exhibits to the registration statement of which this prospectus is a part.

The following section describes certain general terms and provisions of the Debt Securities. The Debt Securities may be issued from time to time in one or more series. The particular terms of each series of Debt Securities offered by any prospectus supplement will be described in that prospectus supplement.

General. An Indenture will not limit the aggregate principal amount of Debt Securities that we may issue. Each Indenture may provide that Debt Securities of any series may be issued under it up to the aggregate principal amount authorized from time to time by us and may be denominated in any currency or currency unit that we designate. We will determine the terms and conditions of each series of Debt Securities, including the maturity, principal and interest, but those terms must be consistent with the Indenture. Unless set forth in the applicable prospectus supplement, neither the Indentures nor the Debt Securities will limit or otherwise restrict the amount of other indebtedness that we may incur or the other securities that we may issue.

The prospectus supplement relating to each series of Debt Securities being offered will specify the particular terms of those Debt Securities. The terms may include:

Debt Securities may be issued as original issue discount Debt Securities (bearing no interest or interest at a rate that at the time of issuance is below market rates) (“Original Issue Discount Securities”), to be sold at a substantial discount below their stated principal amount. There may not be any periodic payments of interest on Original Issue Discount Securities. In the event of an acceleration of the maturity of any Original Issue Discount Security, the amount payable to the holder of such Original Issue Discount Security upon such acceleration will be set forth in the prospectus supplement and determined in accordance with the terms of such security and the applicable Indenture, but will be an amount less than the amount payable at the maturity of the principal of such Original Issue Discount Security. The federal income tax considerations with respect to Original Issue Discount Securities will be explained in the prospectus supplement we prepare for the Original Issue Discount Securities.

Conversion and Exchange Rights. The prospectus supplement will describe, if applicable, the terms on which you may convert Debt Securities into or exchange them for our common stock, our preferred stock or other securities or property. The conversion or exchange may be mandatory or may be at your option. We will describe how the number of shares of our common stock, our preferred stock or other securities or property to be received upon conversion or exchange would be calculated.

Form, Exchange and Transfer. We will issue Debt Securities only in fully registered form, without coupons, and, unless otherwise specified in the prospectus supplement, only in denominations of $1,000 and integral multiples thereof.

The holder of a Debt Security may elect, subject to the terms of the applicable Indenture and the limitations applicable to Global Securities, to exchange them for other Debt Securities of the same series of any authorized denomination and of a like tenor and aggregate principal amount.

Holders of Debt Securities may present them for exchange as provided above or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed, at the office of the transfer agent we designate for the purpose. We will not impose a service charge for any registration of transfer or exchange of Debt Securities, but we may require a payment sufficient to cover any tax or other governmental charge payable in connection with the transfer exchange. We will name the transfer agent in the prospectus supplement. We may designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, but we must maintain a transfer agent in each place of payment for the Debt Securities.

If we redeem the Debt Securities, we will not be required to issue, register the transfer of or exchange any Debt Security during a specified period prior to mailing a notice of redemption. We are not required to register the transfer of or exchange any Debt Security selected for redemption, except the unredeemed portion of the Debt Security being redeemed.

Payment and Paying Agents. Unless otherwise stated in the prospectus supplement, we will pay principal and any premium or interest on a Debt Security to the person in whose name the Debt Security is registered at the close of business on the regular record date for such interest.

Unless otherwise stated in the prospectus supplement, we will pay principal and any premium or interest on the Debt Securities at the office of our designated paying agent, except we may pay interest by check mailed to the address of the person entitled to the payment. Unless we state otherwise in the prospectus supplement, the corporate trust office of the Trustee will be the paying agent for the Debt Securities.

Any other paying agents we designate for the Debt Securities of a particular series will be named in the prospectus supplement. We may designate additional paying agents, rescind the designation of any paying agent or approve a change in the office through which any paying agent acts, but we must maintain a paying agent in each place of payment for the Debt Securities.

The paying agent will return to us all money we pay to it for the payment of the principal, premium or interest on any Debt Security that remains unclaimed for a specified period. The holder thereafter may look only to us for payment.

Global Securities. The Debt Securities of any series may be represented by one or more global securities (each, a “Global Security” and, together, the “Global Securities”) that will have an aggregate principal amount equal to that of the Debt Securities of that series. Each Global Security will be registered in the name of a depositary identified in the prospectus supplement. We will deposit the Global Security with the depositary or a custodian, and the Global Security will bear a legend regarding the restrictions on exchanges and registration of transfer.

No Global Security may be exchanged in whole or in part for Debt Securities registered, and no transfer of a Global Security in whole or in part may be registered, in the name of any person other than the depositary or any nominee of the depositary unless (1) the depositary has notified us that it is unwilling or unable to continue as depositary or (2) an event of default occurs and continues with respect to the Debt Securities. The depositary will determine how all securities issued in exchange for a Global Security will be registered.

As long as the depositary or its nominee is the registered holder of a Global Security, the depositary or the nominee will be considered the sole owner and holder of the Global Security and the underlying Debt Securities. Except as stated above, owners of beneficial interests in a Global Security will not be entitled to have the Global Security or any Debt Security registered in their names, will not receive physical delivery of certificated Debt Securities and will not be considered to be the owners or holders of the Global Security or underlying Debt Securities. We will make all payments of principal, premium and interest on a Global Security to the depositary or its nominee. The laws of some jurisdictions require that certain purchasers of securities take physical delivery of such securities in definitive form. These laws may prevent you from transferring your beneficial interests in a Global Security.

Only institutions that have accounts with the depositary or its nominee and persons that hold beneficial interests through the depositary or its nominee may own beneficial interests in a Global Security. The depositary will credit, on its book-entry registration and transfer system, the respective principal amounts of Debt Securities represented by the Global Security to the accounts of its participants. Ownership of beneficial interests in a Global Security will be shown only on, and the transfer of those ownership interests will be effected only through, records maintained by the depositary or any such participant.

The policies and procedures of the depositary may govern payments, transfers, exchanges and other matters relating to beneficial interests in a Global Security. We and the Trustee assume no responsibility or liability for any aspect of the depositary’s or any participant’s records relating to, or for payments made on account of, beneficial interests in a Global Security.

The specific terms of the depositary arrangement with respect to any series of Debt Securities will be described in the applicable prospectus supplement.

Consolidation, Merger and Sale of Assets. Each Indenture may provide that we may, without the consent of the holders of any of the Debt Securities outstanding under the applicable Indenture, consolidate with, merge into or transfer our assets substantially as an entirety to any person, provided that:

Accordingly, such consolidation, merger or transfer of assets substantially as an entirety, which meets the conditions described above, would not create any Event of Default which would entitle holders of the Debt Securities, or the Trustee on their behalf, to take any of the actions described below under “Events of Default.”

Leveraged and Other Transactions. Unless otherwise specified in the applicable prospectus supplement, the Indentures and the Debt Securities will not contain, among other things, provisions that would protect holders of the Debt Securities in the event of a highly leveraged or other transaction involving us that could adversely affect the holders of Debt Securities.

Modification of the Indentures; Waiver. Each Indenture may provide that, with the consent of the holders of not less than a majority in aggregate principal amount of the outstanding Debt Securities of each affected series, modifications and alterations of such Indenture may be made that affect the rights of the holders of such Debt Securities. However, no such modification or alteration may be made without the consent of the holder of each Debt Security so affected which would, among other things:

The holders of a majority in aggregate principal amount of the outstanding Debt Securities of any series may waive, on behalf of the holders of all Debt Securities of that series, our compliance with certain restrictive provisions of any Indenture. Prior to the acceleration of the maturity of the Debt Securities of any series outstanding under an Indenture, the holders of a majority in aggregate principal amount of the outstanding Debt Securities of any series may waive any past default under an Indenture with respect to Debt Securities of that series, except a default (1) in the payment of principal, premium or interest on any Debt Security of that series or (2) in respect of a covenant or provision of an Indenture that cannot be amended without each holder’s consent.

Except in certain limited circumstances, we may set any day as a record date for the purpose of determining the holders of outstanding Debt Securities of any series entitled to give or take any direction, notice, consent, waiver or other action under an Indenture. In certain limited circumstances, the Trustee may set a record date for action by holders. To be effective, the action must be taken by holders of the requisite principal amount of such Debt Securities within a specified period following the record date.

Events of Default. An Event of Default with respect to the Debt Securities of any series may be defined in an applicable Indenture as:

If an Event of Default (other than an Event of Default relating to events of bankruptcy, insolvency or reorganization) with respect to any series of Debt Securities occurs and is continuing, either the Trustee or the holders of at least 25% in aggregate principal amount of the Debt Securities of such series outstanding may declare the principal amount (or if such Debt Securities are Original Issue Discount Securities, such portion of the principal amount as may be specified in the terms of that series) of all Debt Securities of that series to be immediately due and payable. If an Event of Default relating to events of bankruptcy, insolvency or reorganization with respect to the Debt Securities of any series at the time outstanding shall occur, the principal amount of all the Debt Securities of that series (or, in the case of any such Original Issue Discount Security, such specified amount) will automatically, and without any action by the applicable Trustee or any holder, become immediately due and payable. After any such acceleration, but before a judgment or decree based on acceleration, the holders of a majority in principal amount of the outstanding Debt Securities of that series may, under certain circumstances, rescind and annul such acceleration if all Events of Default, other than the non-payment of accelerated principal (or other specified amount), have been cured or waived as provided in the applicable Indenture. For information as to waiver of defaults, see “Modification of the Indentures; Waiver.”

If an Event of Default occurs and is continuing, the Trustee may, in its discretion, and at the written request of holders of not less than a majority in aggregate principal amount of the Debt Securities of any series, and upon reasonable indemnity against the costs, expenses and liabilities to be incurred in compliance with such request and subject to certain other conditions set forth in the applicable Indenture will, proceed to protect the rights of the holders of all the Debt Securities of such series.

The Indentures will provide that upon the occurrence of an Event of Default relating to payments of principal of, premium, if any, or interest on any Debt Security, we will, upon demand of the Trustee, pay to it, for the benefit of the holder of any such Debt Security, the whole amount then due and payable on such Debt Securities for principal, premium, if any, and interest. The Indentures will further provide that that if we fail to pay such amount upon such demand, the Trustee may, among other things, institute a judicial proceeding for the collection of the amount due.

No holder of a Debt Security of any series may institute any proceeding with respect to an Indenture, or for the appointment of a receiver or a trustee, or for other remedy, unless (1) the holder has previously given the Trustee written notice of a continuing event of default, (2) the holders of at least 25% in aggregate principal amount of the outstanding Debt Securities of that series have made a written request, and the holders have offered reasonable indemnity to the Trustee to institute the proceeding, and (3) the Trustee has failed to institute the proceeding, and has not received a direction inconsistent with the request within 60 days of such notice. The Indenture may also provide that, notwithstanding any other provision of the applicable Indenture, the holder of any Debt Security of any series will have the right to institute suit for the enforcement of any payment of principal of, premium, if any, and interest on such Debt Securities when due and that such right will not be impaired without the consent of such holder.

We are required to file annually with the applicable Trustee a written statement as to the existence or non-existence of defaults under the Indentures or the Debt Securities.

Subordination of the Subordinated Debt Securities. The Subordinated Debt Securities will be our direct, unsecured obligations and, unless otherwise specified in the prospectus supplement relating to a particular series of Subordinated Debt Securities offered by such prospectus supplement, will be subject to the subordination provisions described in this section. Upon any distribution of our assets due to any dissolution, winding up, liquidation or reorganization, the payment of the principal of, premium, if any, and interest on the Subordinated Debt Securities is to be subordinated in right of payment to all Senior Indebtedness. In certain events of bankruptcy or insolvency, the payment of the principal of and interest on the Subordinated Debt Securities will, to the extent provided in a Subordinated Indenture, also be effectively subordinated in right of payment to all General Obligations (as defined below).

Upon any distribution of our assets due to any dissolution, winding up, liquidation or reorganization, the holders of Senior Indebtedness will first be entitled to receive payment in full of all amounts due or to become due before the holders of the Subordinated Debt Securities will be entitled to receive any payment in respect of the Subordinated Debt Securities. If upon any such payment or distribution of assets, after giving effect to such subordination provisions in favor of the holders of Senior Indebtedness, (i) there remain any amounts of cash, property or securities available for payment or distribution in respect of the Subordinated Debt Securities (“Excess Proceeds”) and (ii) if, at such time, any creditors in respect of General Obligations have not received payment in full of all amounts due or to become due on or in respect of such General Obligations, then such Excess Proceeds will first be applied to pay or provide for the payment in full of such General Obligations before any payment or distribution may be made in respect of the Subordinated Debt Securities.

In addition, no payment may be made on the Subordinated Debt Securities, or in respect of any redemption, retirement, purchase or other acquisition of any of the Subordinated Debt Securities, at any time in the event:

Except as described above, our obligation to make payments of the principal of, premium, if any, or interest on the Subordinated Debt Securities will not be affected.

By reason of the subordination in favor of the holders of Senior Indebtedness, in the event of a distribution of assets upon any dissolution, winding up, liquidation or reorganization, our creditors who are not holders of Senior Indebtedness or the Subordinated Debt Securities may recover less, proportionately, than holders of Senior Indebtedness and may recover more, proportionately, than holders of the Subordinated Debt Securities.

Subject to payment in full of all Senior Indebtedness, the holders of Subordinated Debt Securities will be subrogated to the rights of the holders of Senior Indebtedness to receive payments or distributions of cash, property or our securities applicable to Senior Indebtedness. Subject to payment in full of all General Obligations, the holders of the Subordinated Debt Securities will be subrogated to the rights of the creditors in respect of General Obligations to receive payments or distributions of cash, property or our securities applicable to such creditors in respect of General Obligations.

“Senior Indebtedness” for purposes of a Subordinated Indenture is the principal of, premium, if any, and interest on:

The term “indebtedness for money borrowed” as used in this prospectus includes, without limitation, any obligation of, or any obligation guaranteed by us for the repayment of borrowed money, whether or not evidenced by bonds, debentures, notes or other written instruments, and any deferred obligation for the payment of the purchase price of property or assets. A Subordinated Indenture would not limit our issuance of additional Senior Indebtedness.

The Subordinated Debt Securities will rank senior in right of payment to our Junior Subordinated Indebtedness upon any distribution of our assets due to any dissolution, winding up, liquidation or reorganization, to the extent provided in the instruments creating our Junior Subordinated Indebtedness. “Junior Subordinated Indebtedness” is the principal of, premium, if any, and interest on:

Unless otherwise specified in the prospectus supplement relating to a particular series of Subordinated Debt Securities offered thereby, the term “General Obligations” means all obligations to make payment on account of claims in respect of derivative products such as interest and foreign exchange rate contracts, commodity contracts and similar arrangements, other than:

Unless otherwise specified in the prospectus supplement relating to any series of Subordinated Debt Securities, payment of principal of the Subordinated Debt Securities may be accelerated only in case of the bankruptcy, insolvency or reorganization of our company.

Defeasance and Covenant Defeasance. To the extent stated in the prospectus supplement, we may elect to apply the provisions relating to defeasance and discharge of indebtedness, or to defeasance of certain restrictive covenants in the Indentures, to the Debt Securities of any series.

The following is a summary of the rights of our common stock and preferred stock and related provisions of our certificate of incorporation and bylaws. For more detailed information, please see our certificate of incorporation and bylaws, as amended.

Our authorized capital stock consists of 150,000,000 shares of common stock, par value $.0001 per share, and 250,000 shares of preferred stock, par value $.01 per share, issuable in one or more series designated by our board of directors, of which 105,875 shares of our preferred stock have been designated as 5% Series B Cumulative Convertible Perpetual Preferred Stock (“Series B preferred stock”). On July 31, 2010, 112,950,468 shares of our common stock were issued and outstanding and 64,020 shares of our Series B preferred stock were issued and outstanding. No other shares of our preferred stock are issued and outstanding. There are Series 1 preferred shares of our Canadian subsidiary, FuelCell Energy, Ltd., issued and outstanding and convertible into shares of FuelCell Energy, Inc. common stock.

In addition, as of July 31, 2010, there were outstanding options to purchase 5,238,101 shares of our common stock under our equity incentive plans, 1,947,222 shares of our common stock were available for future issuance under our equity incentive plans, and 127,703 shares of our common stock were available for future issuance under our employee stock purchase plan. In addition, as of July 31, 2010, we were obligated, if and when the holder exercises its conversion rights, to issue approximately 193,110 shares of our common stock upon conversion of the Series 1 preferred shares. As of July 31, 2010, there were 662 holders of record of our common stock.

The holders of our common stock have one vote per share. Holders of our common stock are not entitled to vote cumulatively for the election of directors. Generally, all matters to be voted on by shareholders must be approved by a majority, or, in the case of the election of directors, by a plurality, of the votes entitled to be cast at a meeting at which a quorum is present by all shares of our common stock present in person or represented by proxy, voting together as a single class, subject to any voting rights granted to holders of any then outstanding preferred stock.

Holders of our common stock will share ratably in any dividends declared by the board of directors, subject to the preferential rights of any of our preferred stock then outstanding. Dividends consisting of shares of our common stock may be paid to holders of shares of our common stock.

In the event of our liquidation, dissolution or winding up, after payment of liabilities and liquidation preferences on any of our preferred stock then outstanding, the holders of shares of our common stock are entitled to share ratably in all assets available for distribution. Holders of shares of our common stock have no preemptive rights or rights to convert their shares of our common stock into any other securities. There are no redemption or sinking fund provisions applicable to the common stock.

This section describes the general terms of our preferred stock, $0.01 par value, to which any prospectus supplement may relate. Certain terms of any series of our preferred stock offered by any prospectus supplement will be described in such prospectus supplement. If so indicated in the prospectus supplement, the terms of that series may differ from the terms described below. The provisions of our preferred stock described below are not complete. You should refer to our certificate of incorporation and any certificate of amendment to our certificate of incorporation or certificate of designations filed with the SEC in connection with the offering of our preferred stock.

Under our certificate of incorporation, our board of directors has the authority, without further shareholder action, to issue from time to time, preferred stock in one or more series and for such consideration as may be fixed from time to time by our board of directors. Our board also has the authority to fix and determine, in the manner provided by law, the relative rights and preferences of the shares of any series so established, such as dividend and voting rights. Our certificate of incorporation authorizes 250,000 shares of preferred stock. Prior to the issuance of each series of preferred stock, our board will adopt resolutions creating and designating the series as a series of preferred stock. The board of directors may, without shareholder approval, issue preferred stock with voting and other rights that could adversely affect the voting power and other rights of the holders of our common stock and could have anti-takeover effects.

Our preferred stock will have the dividend, liquidation, redemption, voting and conversion rights set forth below unless otherwise specified in the applicable prospectus supplement. You should read the prospectus supplement relating to the particular series of preferred stock offered thereby for specific terms, including:

Unless otherwise specified in the applicable prospectus supplement, the shares of each series of preferred stock will upon issuance rank equally in all respects with each other then outstanding series of preferred stock.

Preferred stock could be issued quickly with terms that could delay or prevent a change of control or make the removal of management more difficult. Additionally, the issuance of preferred stock may decrease the market price of our common stock and may adversely affect the voting and other rights of the holders of our common stock.

Any series of our preferred stock will, with respect to dividend rights and rights on liquidation, winding up or dissolution, rank:

The holders of our preferred stock will be entitled to receive, when, as and if declared by our board of directors, dividends at such rates and on such dates as will be specified in the applicable prospectus supplement. Such rates may be fixed or variable or both. If variable, the formula used for determining the dividend rate for each dividend period will be specified in the applicable prospectus supplement. Dividends will be payable to the holders of record as they appear on our stock books on such record dates as will be fixed by our board. Dividends may be paid in the form of cash, preferred stock (of the same or a different series) or our common stock, in each case as specified in the applicable prospectus supplement.

Dividends on any series of our preferred stock may be cumulative or noncumulative, as specified in the applicable prospectus supplement. If the dividends on a series of our preferred stock are noncumulative (“Noncumulative Preferred Stock”), and our board of directors fails to declare a dividend payable on a dividend payment date, then the holders of such preferred stock will have no right to receive a dividend in respect to the dividend period relating to such dividend payment date, and we will not be obligated to pay the dividend accrued for such period, whether or not dividends on such preferred stock are declared or paid on any future dividend payment dates.

We will not declare or pay or set apart for payment any dividends on any series of our preferred stock that rank, as to dividends, on a parity with or junior to the outstanding preferred stock of any series unless (i) if such outstanding preferred stock has a cumulative dividend (“Cumulative Preferred Stock”), full cumulative dividends have been or contemporaneously are declared and paid or declared and a sum sufficient for the payment thereof set apart for such payment on such preferred stock for all dividend periods terminating on or prior to the date of payment of any such dividends on such other series of the preferred stock or (ii) if such outstanding preferred stock is Noncumulative Preferred Stock, full dividends for the then-current dividend period on such preferred stock have been or contemporaneously are declared and paid or declared and a sum sufficient for the payment thereof set apart for such payment.

Until full dividends are paid (or declared and payment is set aside) on our preferred stock ranking equal as to dividends, then:

We will not owe any interest, or any money in lieu of interest, on any dividend payment on any series of the preferred stock that may be past due.

A series of our preferred stock may be redeemable, in whole or in part, at our option, and may be subject to mandatory redemption pursuant to a sinking fund or otherwise, in each case upon terms, at the times and at the redemption prices specified in the applicable prospectus supplement. Redeemed shares of our preferred stock will become authorized but unissued shares of preferred stock that we may issue in the future.

The prospectus supplement relating to a series of our preferred stock that is subject to mandatory redemption will specify the number of shares of such preferred stock that we will redeem each year and the redemption price per share. If shares of our preferred stock are redeemed, we will pay all accrued and unpaid dividends thereon (which will not, if such preferred stock is Noncumulative Preferred Stock, include any accumulation in respect of unpaid dividends for prior dividend periods) up to but excluding the date of redemption. The redemption price may be payable in cash or other property, as specified in the applicable prospectus supplement. If the redemption price for our preferred stock of any series is payable only from the net proceeds of the issuance of our capital stock, the terms of such preferred stock may provide that, if no such capital stock will have been issued or to the extent the net proceeds from any issuance are insufficient to pay in full the aggregate redemption price then due, such preferred stock will automatically and mandatorily be converted into shares of our applicable capital stock pursuant to conversion provisions specified in the applicable prospectus supplement.

If fewer than all the outstanding shares of our preferred stock of any series are to be redeemed, our board will determine the number of shares to be redeemed. We will redeem the shares pro rata from the holders of record of such shares in proportion to the number of such shares held by such holders (with adjustments to avoid redemption of fractional shares) or by lot or by any other method as may be determined by our board.

Even though the terms of a series of the Cumulative Preferred Stock may permit redemption of such preferred stock in whole or in part, if any dividends, including accumulated dividends, on that series are past due:

The prohibition discussed in the preceding sentence will not prohibit us from purchasing or acquiring preferred stock of that series pursuant to a purchase or exchange offer if we make the offer on the same terms to all holders of that series.

The prospectus supplement relating to a series of convertible preferred stock will describe the terms on which shares of such series are convertible into our common stock.

Unless the applicable prospectus supplement states otherwise, if we voluntarily or involuntarily liquidate, dissolve or wind up our business, the holders of our preferred stock will be entitled to receive out of our assets available for distribution to stockholders, before any distribution of assets is made to holders of our common stock or any other class or series of shares ranking junior to such preferred stock upon liquidation, liquidating distributions in the amount of the liquidation preference of such preferred stock plus accrued and unpaid dividends (which will not, if such preferred stock is Noncumulative Preferred Stock, include any accumulation in respect of unpaid dividends for prior dividend periods). If we voluntarily or involuntarily liquidate, dissolve or wind up our business and the amounts payable with respect to our preferred stock of any series and any of our other securities ranking equal as to any such distribution are not paid in full, the holders of such preferred stock and of such other shares will share ratably in any such distribution of our assets in proportion to the full respective preferential amounts to which they are entitled. After payment of the full amount of the liquidating distribution to which they are entitled, the holders of our preferred stock of any series will not be entitled to any further participation in any distribution of our assets.

Except as described in this section or in the applicable prospectus supplement, or except as expressly required by applicable law, the holders of our preferred stock will not be entitled to vote. If the holders of a series of our preferred stock are entitled to vote and the applicable prospectus supplement does not state otherwise, each such share will be entitled to one vote on matters on which holders of such series of preferred stock are entitled to vote. For any series of our preferred stock having one vote per share, the voting power of such series, on matters on which holders of such series and holders of other series of our preferred stock are entitled to vote as a single class, will depend on the number of shares in such series, not the aggregate stated value, liquidation preference or initial offering price of the shares of such series of preferred stock.

Unless we receive the consent of the holders of an outstanding series of preferred stock and the outstanding shares of all other series of preferred stock which (i) rank equal with such series either as to dividends or the distribution of assets upon liquidation, dissolution or winding up of our business and (ii) have voting rights that are exercisable and that are similar to those of such series, we will not:

This consent must be given by the holders of a majority of all such outstanding preferred stock described in the preceding sentence, voting together as a single class. We will not be required to obtain this consent with respect to the actions listed in the second bullet point above, however, if we only (i) increase the amount of the authorized preferred stock, (ii) create and issue another series of preferred stock, or (iii) increase the amount of authorized shares of any series of preferred stock, if such preferred stock in each case ranks equal with or junior to the preferred stock with respect to the payment of dividends and the distribution of assets upon liquidation, dissolution or winding up of our business.

On November 11, 2004, we entered into a purchase agreement with Citigroup Global Markets Inc., RBC Capital Markets Corporation, Adams Harkness, Inc., and Lazard Freres & Co., LLC (the “Initial Purchasers”) for the private placement under Rule 144A of up to 135,000 shares of our 5% Series B Cumulative Convertible Perpetual Preferred Stock (Liquidation Preference $1,000). On November 17, 2004 and January 25, 2005, we closed on the sale of 100,000 shares and 5,875 shares, respectively, of Series B preferred stock to the Initial Purchasers.

At July 31, 2010, there were 250,000 preferred shares authorized of which 64,020 Series B preferred shares were issued and outstanding. The carrying value of the Series B preferred stock as of October 31, 2009, 2008 and 2007 represents the net proceeds to us of approximately $60 million.

The following is a summary of certain provisions of our Series B preferred stock. The resale of the shares of our Series B preferred stock and the resale of the shares of our common stock issuable upon conversion of the shares of our Series B preferred stock are covered by a registration rights agreement.

Shares of our Series B preferred stock rank with respect to dividend rights and rights upon our liquidation, winding up or dissolution:

The Series B preferred stock pays cumulative annual dividends of $50 per share which are payable quarterly in arrears on February 15, May 15, August 15 and November 15, which commenced on February 15, 2005, when, as and if declared by the board of directors. Dividends will be paid on the basis of a 360-day year consisting of twelve 30-day months. Dividends on the shares of our Series B preferred stock will accumulate and be cumulative from the date of original issuance. Accumulated dividends on the shares of our Series B preferred stock will not bear any interest.

The dividend rate on the Series B preferred stock is subject to upward adjustment as set forth in the certificate of designation of the Series B preferred stock if we fail to pay, or to set apart funds to pay, dividends on the shares of our Series B preferred stock for any quarterly dividend period. The dividend rate on the Series B preferred stock is also subject to upward adjustment as set forth in the registration rights agreement entered into with the Initial Purchasers if we fail to satisfy our registration obligations with respect to the Series B preferred stock (or the underlying common shares) set forth in the registration rights agreement.

No dividends or other distributions may be paid or set apart for payment upon our common shares (other than a dividend payable solely in shares of a like or junior ranking) unless all accumulated and unpaid dividends have been paid or funds or shares of common stock therefore have been set apart on our Series B preferred stock.

The Series B preferred stock has a liquidation preference of $1,000 per share. Upon any voluntary or involuntary liquidation, dissolution or winding up of FuelCell resulting in a distribution of assets to the holders of any class or series of our capital stock, each holder of shares of our Series B preferred stock will be entitled to payment out of our assets available for distribution of an amount equal to the liquidation preference per share of Series B preferred stock held by that holder, plus all accumulated and unpaid dividends on those shares to the date of that liquidation, dissolution, or winding up, before any distribution is made on any junior shares, including shares of our common stock, but after any distributions on any of our indebtedness or senior shares (if any). After payment in full of the liquidation preference and all accumulated and unpaid dividends to which holders of shares of our Series B preferred stock are entitled, holders of shares of our Series B preferred stock will not be entitled to any further participation in any distribution of our assets.

A share of our Series B preferred stock may be converted at any time, at the option of the holder, into 85.1064 shares of our common stock (which is equivalent to an initial conversion price of $11.75 per share) plus cash in lieu of fractional shares. The conversion rate is subject to adjustment upon the occurrence of certain events, as described below, but will not be adjusted for accumulated and unpaid dividends. Upon conversion, holders of Series B preferred stock will not receive a cash payment for any accumulated dividends. Instead accumulated dividends, if any, will be cancelled.

After November 20, 2009 we may, at our option, cause shares of our Series B preferred stock to be automatically converted into that number of shares of our common stock that are issuable at the then prevailing conversion rate. We may exercise our conversion right only if the closing price of our common stock exceeds 150% of the then prevailing conversion price for 20 trading days during any consecutive 30 trading day period, as described in the certificate of designation for the Series B preferred stock.

If holders of shares of our Series B preferred stock elect to convert their shares in connection with certain fundamental changes (as described below and in the certificate of designation), we will in certain circumstances discussed below increase the conversion rate by a number of additional shares of common stock upon conversion or, in lieu thereof, we may in certain circumstances elect to adjust the conversion rate and related conversion obligation so that shares of our Series B preferred stock are converted into shares of the acquiring or surviving company, in each case as described in the certificate of designation.

The adjustment of the conversion price of the Series B preferred stock is to prevent dilution of the interests of the holders of the Series B preferred stock, including on account of the following:

Shares of our Series B preferred stock will not be redeemable by us, except in the case of a fundamental change (as described below and in the certificate of designation) whereby holders may require us to purchase all or part of their shares at a redemption price equal to 100% of the liquidation preference of the shares of Series B preferred stock to be repurchased, plus accrued and unpaid dividends, if any. We may, at our option, elect to pay the redemption price in cash or, in shares of our common stock valued at a discount of 5% from the market price of shares of our common stock, or any combination thereof. Notwithstanding the foregoing, we may only pay such redemption price in shares of our common stock that are registered under the Securities Act of 1933, as amended (the “Securities Act”) and eligible for immediate sale in the public market by non-affiliates of FuelCell.

Redemption by holders of the Series B preferred stock can only occur upon a fundamental change, which we do not consider to be probable at this time. Accordingly, future adjustments of the redemption price will only be made if and when a fundamental change is considered probable.

A “fundamental change” will be deemed to have occurred if any of the following occurs:

(1) any “person” or “group” is or becomes the beneficial owner, directly or indirectly, of 50% or more of the total voting power of all classes of our capital stock then outstanding and normally entitled to vote in the election of directors;

(2) during any period of two consecutive years, individuals who at the beginning of such period constituted the Board of Directors (together with any new directors whose election by our Board of Directors or whose nomination for election by our shareholders was approved by a vote of two-thirds of our directors then still in office who were either directors at the beginning of such period or whose election of nomination for election was previously so approved) cease for any reason to constitute a majority of our directors then in office;

(3) the termination of trading of our common stock on the Nasdaq Stock Market and such shares are not approved for trading or quoted on any other U.S. securities exchange; or

(4) we consolidate with or merge with or into another person or another person merges with or into us or the sale, assignment, transfer, lease, conveyance or other disposition of all or substantially all of our assets and certain of our subsidiaries, taken as a whole, to another person and, in the case of any such merger or consolidation, our securities that are outstanding immediately prior to such transaction and which represent 100% of the aggregate voting power of our voting stock are changed into or exchanged for cash, securities or property, unless pursuant to the transaction such securities are changed into securities of the surviving person that represent, immediately after such transaction, at least a majority of the aggregate voting power of the voting stock of the surviving person.

Notwithstanding the foregoing, holders of shares of Series B preferred stock will not have the right to require us to repurchase their shares if either:

Holders of shares of our Series B preferred stock have no voting rights unless (1) dividends on any shares of our Series B preferred stock or any other class or series of stock ranking on a parity with the shares of our Series B preferred stock with respect to the payment of dividends shall be in arrears for dividend periods, whether or not consecutive, containing in the aggregate a number of days equivalent to six calendar quarters or (2) we fail to pay the repurchase price, plus accrued and unpaid dividends, if any, on the fundamental change repurchase date for shares of our Series B preferred stock following a fundamental change (as described in the certificate of designation for the Series B preferred stock). In each such case, the holders of shares of our Series B preferred stock (voting separately as a class with all other series of other preferred stock on parity with our Series B preferred stock upon which like voting rights have been conferred and are exercisable, if any) will be entitled to vote for the election of two directors in addition to those directors on the board of directors at such time at the next annual meeting of shareholders and each subsequent meeting until the repurchase price or all dividends accumulated on the shares of our Series B preferred stock have been fully paid or set aside for payment. The term of office of all directors elected by the holders of shares of our Series B preferred stock will terminate immediately upon the termination of the right of holders of shares of our Series B preferred stock to vote for directors.

So long as any shares of our Series B preferred stock remain outstanding, we will not, without the consent of the holders of at least two-thirds of the shares of our Series B preferred stock outstanding at the time (voting separately as a class with all other series of preferred stock, if any, on parity with our Series B preferred stock upon which like voting rights have been conferred and are exercisable) issue or increase the authorized amount of any class or series of shares ranking senior to the outstanding shares of our Series B preferred stock as to dividends or upon liquidation. In addition, we will not, subject to certain conditions, amend, alter or repeal provisions of our certificate of incorporation, including the certificate of designation relating to our Series B preferred stock, whether by merger, consolidation or otherwise, so as to adversely amend, alter or affect any power, preference or special right of the outstanding shares of our Series B preferred stock or the holders thereof without the affirmative vote of not less than two-thirds of the issued and outstanding shares of our Series B preferred stock.

On August 4, 2003, we entered into a combination agreement with Global Thermoelectric Inc. (“Global”) to combine Global with us in a share-for-share exchange pursuant to a Plan of Arrangement subject to approval by the Court of Queen’s Bench of Alberta, Canada. On October 31, 2003, our shareholders and the shareholders of Global approved the combination. On October 31, 2003, the Court of Queen’s Bench of Alberta issued an order approving the combination. On November 3, 2003, the combination transaction was consummated. In the aggregate, we issued approximately 8.2 million shares of our common stock and exchangeable shares in the acquisition. Following our acquisition of Global, Global’s Series 2 preferred shares remained outstanding in Global. At the time of the sale of our thermoelectric generator business, the holder of the Series 2 preferred shares exchanged them for Series 1 Class A cumulative redeemable exchangeable preferred shares (which were referred to as the Series 1 preferred shares) issued by FuelCell Energy, Ltd., one of our indirect, wholly-owned subsidiaries. We have guaranteed the obligations of FuelCell Energy, Ltd. under the Series 1 preferred shares.

The Series 1 preferred shares may be converted into shares of our common stock at the following conversion prices:

The foregoing conversion prices are subject to adjustment for certain subsequent events. As illustrated below, the number of shares of our common stock issuable upon conversion of the Series 1 preferred shares after July 31, 2020 may be significantly greater than the number of shares issuable prior to that time.

The following examples illustrate the number of shares of our common stock that we will be required to issue to the holder(s) of the Series 1 preferred shares if and when the holder(s) exercise their conversion rights pursuant to the terms of the Series 1 preferred shares. The following examples are based upon Cdn.$25.0 million of Series 1 preferred shares outstanding (which is the amount currently outstanding) and assume that all accrued dividends on the Series 1 preferred shares have been paid through the time of the conversion and, in the case of conversions occurring after July 31, 2020, that the exchange rate for conversion of Canadian dollars into US dollars is Cdn.$1.04 for each U.S.$1.00 (exchange rate on September 9, 2010) at the time of the conversion:

Subject to the Business Corporations Act (Alberta), the holder of the Series 1 preferred shares is not entitled to receive notice of or to attend or vote at any meeting of the FuelCell Energy, Ltd. Common shareholders. At present, we own all of the FuelCell Energy, Ltd. common stock.

Quarterly dividends of Cdn.$312,500 accrue on the Series 1 preferred shares (subject to possible reduction pursuant to the terms of the Series 1 preferred shares on account of increases in the price of our common stock). We have agreed to pay a minimum of Cdn.$500,000 in cash or common stock annually to Enbridge, the sole current holder of the Series 1 preferred shares, as long as Enbridge holds the shares. Interest accrues on cumulative unpaid dividends at a 2.45% quarterly rate, compounded quarterly, until payment thereof. All cumulative unpaid dividends must be paid by December 31, 2010. Subsequent to 2010, FuelCell Energy, Ltd. would be required to pay annual dividend amounts totaling Cdn.$1.25 million so long as the Series 1 preferred shares remain outstanding. Cumulative unpaid dividends and accrued interest of $10.6 million on the Series 1 preferred shares were outstanding as of September 9, 2010. We have guaranteed the dividend obligations of FuelCell Energy, Ltd. to the Series 1 preferred shareholders.

Subject to the Business Corporations Act (Alberta), we may redeem the Series 1 preferred shares, in whole or part, at any time, if on the day that the notice of redemption is first given, the volume-weighted average price at which our common stock is traded on the applicable stock exchange during the 20 consecutive trading days ending on a date not earlier than the fifth preceding day on which the notice of redemption is given was not less than a 20% premium to the current conversion price on payment of Cdn.$25.00 per Series 1 preferred share to be redeemed, together with an amount equal to all accrued and unpaid dividends to the date fixed for redemption. On or after July 31, 2010, the Series 1 preferred shares are redeemable by us at any time on payment of Cdn.$25.00 per Series 1 preferred share to be redeemed together with an amount equal to all accrued and unpaid dividends to the date fixed for redemption. Holders of the Series 1 preferred shares do not have any mandatory or conditional redemption rights. There are currently 1,000,000 Series 1 preferred shares outstanding.

In the event of the liquidation, dissolution or winding up of FuelCell Energy, Ltd., whether voluntary or involuntary, or any other distribution of its assets among its shareholders for the purpose of winding up its affairs, the holder of the Series 1 preferred shares will be entitled to receive the amount paid on such Series 1 preferred shares (currently Cdn.$25.0 million) together with an amount equal to all accrued and unpaid dividends thereon, before any amount will be paid or any of FuelCell Energy, Ltd.’s property or assets will be distributed to the holders of FuelCell Energy, Ltd.’s common stock. After payment to the holder of the Series 1 preferred shares of the amounts payable to them, the holder of the Series 1 preferred shares will not be entitled to share in any other distribution of FuelCell Energy, Ltd.’s property or assets. We have guaranteed the liquidation obligations of FuelCell Energy, Ltd. under the Series 1 preferred shares.

A number of provisions of our certificate of incorporation and by-laws concern matters of corporate governance and the rights of shareholders. Some of these provisions, including, but not limited to, the inability of shareholders to take action by unanimous written consent, supermajority voting provisions with respect to any amendment of voting rights provisions, the filling of vacancies on the board of directors by the affirmative vote of a majority of the remaining directors, and the ability of the board of directors to issue shares of preferred stock and to set the voting rights, preferences and other terms thereof, without further shareholder action, may be deemed to have anti-takeover effect and may discourage takeover attempts not first approved by the board of directors, including takeovers which shareholders may deem to be in their best interests. If takeover attempts are discouraged, temporary fluctuations in the market price of shares of our common stock, which may result from actual or rumored takeover attempts, may be inhibited. These provisions, together with the ability of the board of directors to issue preferred stock without further shareholder action, could also delay or frustrate the removal of incumbent directors or the assumption of control by shareholders, even if the removal or assumption would be beneficial to our shareholders. These provisions could also discourage or inhibit a merger, tender offer or proxy contest, even if favorable to the interests of shareholders, and could depress the market price of our common stock. The board of directors believes these provisions are appropriate to protect our interests and the interests of our shareholders. The board of directors has no present plans to adopt any further measures or devices which may be deemed to have an “anti-takeover effect.”

We are subject to Section 203 of the Delaware General Corporation Law, which prohibits a publicly-held Delaware corporation from engaging in a “business combination,” except under certain circumstances, with an “interested shareholder” for a period of three years following the date such person became an “interested shareholder” unless:

The term “interested shareholder” generally is defined as a person who, together with affiliates and associates, owns, or, within the three years prior to the determination of interested shareholder status, owned, 15 percent or more of a corporation’s outstanding voting stock. The term “business combination” includes mergers, asset or stock sales and other similar transactions resulting in a financial benefit to an interested shareholder. Section 203 makes it more difficult for an “interested shareholder” to effect various business combinations with a corporation for a three-year period. The existence of this provision would be expected to have an anti-takeover effect with respect to transactions not approved in advance by the board of directors, including discouraging attempts that might result in a premium over the market price for the shares of our common stock held by shareholders. A Delaware corporation may “opt out” of Section 203 with an express provision in its original certificate of incorporation or any amendment thereto. Our certificate of incorporation does not contain any such exclusion.

Our common stock is listed on the Nasdaq Global Market under the symbol “FCEL”.

The transfer agent and registrar for our common stock and preferred stock is American Stock Transfer & Trust Company, New York, New York.

We may issue warrants for the purchase of common stock, debt securities or other securities registered pursuant to this registration statement and described in this prospectus. We may issue warrants independently or together with other securities that may be attached to or separate from the warrants. We will issue each series of warrants under a separate warrant agreement that will be entered into between us and a bank or trust company, as warrant agent, and will be described in the prospectus supplement relating to the particular issue of warrants. The warrant agent will act solely as our agent in connection with the warrants of such series and will not assume any obligation or relationship of agency for or with holders or beneficial owners of warrants. The following describes certain general terms and provisions of debt warrants or common stock warrants we may offer. We will set forth further terms of the debt warrants, common stock warrants or warrants to purchase other securities and the applicable warrant agreement in the applicable prospectus supplement.

The applicable prospectus supplement will describe the terms of any debt warrants, including the following:

The applicable prospectus supplement will describe the terms of any common stock warrants, including the following:

We may sell the securities from time to time pursuant to underwritten public offerings, negotiated transactions, block trades or a combination of these methods. We may sell the securities (1) through underwriters or dealers, (2) through agents and/or (3) directly to one or more purchasers. We may distribute the securities from time to time in one or more transactions:

We may solicit directly offers to purchase the securities being offered by this prospectus. We may also designate agents to solicit offers to purchase the securities from time to time. We will name in a prospectus supplement any agent involved in the offer or sale of our securities.

If we utilize a dealer in the sale of the securities being offered by this prospectus, we will sell the securities to the dealer, as principal. The dealer may then resell the securities to the public at varying prices to be determined by the dealer at the time of resale.

If underwriters are used in the sale of any the securities, the securities will be acquired by the underwriters for their own account and may be resold from time to time in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. The securities may be either offered to the public through underwriting syndicates represented by managing underwriters, or directly by underwriters. Generally, the underwriters’ obligations to purchase the securities will be subject to certain conditions precedent. The underwriters will be obligated to purchase all of the securities if they purchase any of the securities.

We may sell the securities through agents from time to time. The applicable prospectus supplement will name any agent involved in the offer or sale of the securities and any commissions paid to them. Generally, any agent will be acting on a best efforts basis for the period of its appointment. In addition, we may enter into derivative, sale or forward sale transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with such transaction, the third parties may, pursuant to this prospectus and the applicable prospectus supplement, sell the securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities borrowed from us or others to settle such sales and may use securities received

from us or others to settle those sales to close out any related short positions. The third party in such sale transactions will be an underwriter and will be identified in the applicable prospectus supplement (or a post-effective amendment). We may also loan or pledge the securities covered by this prospectus and the applicable prospectus supplement to third parties, who may sell the loaned securities or, in an event of default in the case of a pledge, sell the pledged securities pursuant to this prospectus and the applicable prospectus supplement.

The Underwriters, broker-dealers and agents that participate in the distribution of the securities may be deemed to be “underwriters” as defined by the Securities Act. Any commissions paid or any discounts or concessions allowed to any such persons, and any profits they receive on resale of the securities, may be deemed to be underwriting discounts and commissions under the Securities Act.

Agents, underwriters, and dealers may be entitled under relevant agreements with us to indemnification by us against certain liabilities, including liabilities under the Securities Act, or to contribution with respect to payments which such agents, underwriters and dealers may be required to make in respect thereof. The terms and conditions of any indemnification or contribution will be described in the applicable prospectus supplement.

Underwriters, broker-dealers or agents may receive compensation in the form of commissions, discounts or concessions from us. Underwriters, broker-dealers or agents may also receive compensation from the purchasers of the securities for whom they act as agents or to whom they sell as principals, or both. Compensation as to a particular underwriter, broker-dealer or agent might be in excess of customary commissions and will be in amounts to be negotiated in connection with transactions involving the securities. In effecting sales, broker-dealers engaged by us may arrange for other broker-dealers to participate in the resales. Maximum compensation to any underwriters, dealers or agents will not exceed any applicable NASD limitations.

Underwriters or agents may purchase and sell the securities in the open market. These transactions may include over-allotments, stabilizing transactions, syndicate covering transactions and penalty bids. Over-allotments involve sales in excess of the offering size, which creates a short position. Stabilizing transactions consist of bids or purchases for the purpose of preventing or retarding a decline in the market price of the securities and are permitted so long as the stabilizing bids do not exceed a specified maximum. Syndicate covering transactions involve the placing of any bid on behalf of the underwriting syndicate or the effecting of any purchase to reduce a short position created in connection with an offering. The underwriters or agents also may impose a penalty bid, which permits them to reclaim selling concessions allowed to syndicate members or certain dealers if they repurchase the securities in stabilizing or covering transactions. These activities may stabilize, maintain or otherwise affect the market price of the securities, which may be higher than the price that might otherwise prevail in the open market. These activities, if begun, may be discontinued at any time. These transactions may be effected on any exchange on which the securities are traded, in the over-the-counter market or otherwise.

Except as indicated in the applicable prospectus supplement, the securities are not expected to be listed on any securities exchange, except for our common stock, which is quoted on the Nasdaq Global Market under the symbol “FCEL”, and no underwriters will be obligated to make a market in these securities. We cannot predict the activity or liquidity of any trading in these securities.

DISCLOSURE OF COMMISSION POSITION ON INDEMNIFICATION FOR SECURITIES ACT LIABILITIES

Our certificate of incorporation provides that none of our directors will be personally liable to us or our shareholders for monetary damages for breach of fiduciary duty as a director, except to the extent such exemption from liability or limitation thereof is not permitted under the Delaware General Corporation Law. Our by-laws provide for indemnification of our officers and directors to the fullest extent permitted by applicable law. Insofar as indemnification for liabilities under the Securities Act may be permitted to directors, officers or controlling persons of the Company pursuant to the certificate of incorporation, bylaws or applicable law, or otherwise, we have been advised that in the opinion of the SEC such indemnification is against public policy as expressed in the Securities Act and is therefore unenforceable.

The validity of the securities offered hereby has been passed upon for us by Robinson & Cole LLP, Stamford, Connecticut.

The consolidated financial statements of FuelCell Energy, Inc. and subsidiaries as of October 31, 2009 and 2008, and for each of the years in the three-year period ended October 31, 2009, and management’s assessment of the effectiveness of internal control over financial reporting as of October 31, 2009 have been incorporated by reference herein and in the registration statement in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing.

We have filed with the SEC a registration statement on Form S-3 under the Securities Act with respect to our securities offered hereby. This prospectus, which constitutes a part of the registration statement, does not contain all of the information set forth in the registration statement or the exhibits and schedules filed therewith. We have omitted certain parts of the registration statement as permitted by the rules and regulations of the SEC. For further information about us and our securities offered hereby, reference is made to the registration statement and the exhibits and schedules filed therewith. Statements contained in this prospectus regarding the contents of any contract or any other document that is filed as an exhibit to the registration statement are not necessarily complete, and each such statement is qualified in all respects by reference to the full text of such contract or other document filed as an exhibit to the registration statement. A copy of the registration statement and the exhibits and schedules filed therewith may be inspected without charge at the public reference room maintained by the SEC, located at 100 F Street, N.E., Washington, D.C. 20549, and copies of all or any part of the registration statement may be obtained from such offices upon the payment of the fees prescribed by the SEC. Please call the SEC at 1-800-SEC-0330 for further information about the public reference room. The SEC also maintains an Internet web site that contains reports, proxy and information statements and other information regarding registrants that file electronically with the SEC. The address of the site is http://www.sec.gov.

We are subject to the informational requirements of the Securities Exchange Act of 1934 (the “Exchange Act”) and, therefore, we file annual, quarterly and current reports, proxy statements and other information with the SEC. Such periodic reports, proxy statements and other information are available for inspection and copying at the public reference room and web site of the SEC referred to above. Our common stock is quoted on the Nasdaq Global Market, and you may also inspect and copy our SEC filings at the offices of the National Association of Securities Dealers, Inc. located at 1735 K Street, N.W., Washington, D.C. 20006.

You should rely only on the information provided in this prospectus and the registration statement. We have not authorized anyone else to provide you with different information. Our securities are not being offered in any state where the offer is not permitted. You should assume that the information in this prospectus is accurate only as of the dates of those documents. Our business, financial condition, results of operations and prospects may have changed since those dates.


	Per Note			Total
Offering Price		100.0	%	$	38,000,000
Underwriters’ discount		5.5	%	$	2,090,000
Proceeds to FuelCell (before expenses)		94.5	%	$	35,910,000


	Page
PROSPECTUS SUPPLEMENT
ABOUT THIS PROSPECTUS SUPPLEMENT		S-3
PROSPECTUS SUPPLEMENT SUMMARY		S-4
FUELCELL ENERGY, INC.		S-4
THE OFFERING		S-5
RISK FACTORS		S-8
FORWARD-LOOKING STATEMENTS		S-19
USE OF PROCEEDS		S-20
RATIO OF EARNINGS TO COMBINED FIXED CHARGES AND PREFERRED DIVIDENDS		S-21
CAPITALIZATION		S-21
DIVIDEND POLICY		S-22
DESCRIPTION OF THE NOTES		S-22
UNDERWRITING		S-33
LEGAL MATTERS		S-36
WHERE YOU CAN FIND ADDITIONAL INFORMATION		S-36
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE		S-36

PROSPECTUS

FORWARD-LOOKING STATEMENTS		3
ABOUT THIS PROSPECTUS		3
FUELCELL ENERGY, INC.		3
RISK FACTORS		5
RATIO OF EARNINGS TO COMBINED FIXED CHARGES AND PREFERRED DIVIDENDS		18
USE OF PROCEEDS		18
DESCRIPTION OF DEBT SECURITIES		18
DESCRIPTION OF CAPITAL STOCK		26
DESCRIPTION OF WARRANTS		35
PLAN OF DISTRIBUTION		37
DISCLOSURE OF COMMISSION POSITION ON INDEMNIFICATION FOR SECURITIES ACT LIABILITIES		38
LEGAL MATTERS		38
EXPERTS		39
WHERE YOU CAN FIND MORE INFORMATION		39
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE		39


	As of April 30, 2013
	Actual			As Adjusted
	(Dollars in thousands)

Cash and cash equivalents	$	56,039		$	91,649

Long term debt, including the notes offered hereby (1)	$	6,844		$	44,844

Shareholders’ equity:
Common stock (par value $0.0001 per share) (2)		19			19
Additional paid in capital (2)		753,477			753,477
Accumulated deficit		(755,876	)		(755,876	)
Accumulated other comprehensive income		87			87
Common stock held in treasury		(53	)		(53	)
Deferred compensation		53			53
Stockholders’ equity		(2,293	)		(2,293	)

Total capitalization	$	46,902		$	44,512


Underwriter	Principal Amount of Notes

Lazard Capital Markets LLC	$	24,700,000
Stifel, Nicolaus & Company, Incorporated	$	13,300,000

Total:	$	38,000,000


	Per Note		TOTAL
Public offering price	$	1,000	$	38,000,000
Underwriting discounts and commissions		55		2,090,000
Proceeds, before expenses, to us	$	945	$	35,910,000