Form S-3

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this Registration Statement.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. ¨

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box. x

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ¨

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ¨

If delivery of the prospectus is expected to be made pursuant to Rule 434, please check the following box. ¨

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. The selling stockholder may not sell these securities until the Registration Statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting offers to buy these securities in any state where the offer or sale is not permitted.

This prospectus relates to shares of common stock, $.01 par value, of OYO Geospace Corporation.

We will provide the specific terms of the common stock offering in supplements to this prospectus. This prospectus may not be used to sell our common stock unless it is accompanied by a prospectus supplement.

The stockholder named in this prospectus under the heading “Selling Stockholder” is offering all of the shares of common stock offered hereby. We will not receive proceeds from the sale of these shares and will not bear any expenses incident to the offering and sale of the shares.

The selling stockholder may sell these shares from time to time in transactions on the NASDAQ National Market, on any stock exchange on which the common stock may be listed at the time of sale, in the over-the-counter market, in negotiated transactions or otherwise. Sales of shares of common stock may be made at fixed prices which may be changed, at market prices prevailing at the time of sale, at prices related to such prevailing market prices or at negotiated prices.

Our common stock is traded on the NASDAQ National Market (NASDAQ) under the symbol “OYOG”. On April 21, 2005, the last reported sale price of our common stock on NASDAQ was $18.73.

You should carefully review and consider the information under the heading “Risk Factors” in this prospectus and under the heading “Risk Factors” in our latest annual report on Form 10-K incorporated by reference in this prospectus before investing in our common stock.

These securities have not been approved or disapproved by the Securities and Exchange Commission or any state securities commission, nor has the Securities and Exchange Commission or any state securities commission passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

We have not authorized any selling stockholder, dealer, salesman or other person to give you any information or to make any representations other than those contained in this prospectus and in the documents we incorporate into this prospectus. You should not rely on any information or representations that are not contained in this prospectus or in the documents we incorporate into this prospectus.

This prospectus is not an offer to sell, or a solicitation of an offer to buy, the securities offered hereby in any jurisdiction to any person to whom it is unlawful to make an offer or solicitation in that jurisdiction.

Delivery of this prospectus at any time does not imply that the information contained herein is correct as of any time subsequent to its date.

As used in this prospectus, the terms “OYO Geospace,” “company,” “we,” “our,” “ours” and “us” refer to OYO Geospace Corporation and its consolidated subsidiaries, except where the context otherwise requires or as otherwise indicated.

This summary highlights selected information about us and this offering by the selling stockholder contained elsewhere in this prospectus and the documents incorporated by reference into this prospectus. This summary is not complete and may not contain all of the information that is important to you. We encourage you to read this prospectus, including the information under the caption “Risk Factors,” the information we incorporate by reference and the documents to which we refer you in their entirety.

We design and manufacture instruments and equipment used in the acquisition and processing of seismic data. We also design and manufacture thermal imaging equipment and distribute dry thermal film products to the thermal solutions industry.

Geoscientists use seismic data to map potential or existing oil and gas bearing formations and the geologic structures that surround them. Seismic data is used primarily in connection with the exploration, development and production of oil and gas reserves.

Seismic data acquisition is generally conducted by combining a seismic energy source and a data recording system. On land, our customers use our geophones, leader wire cables and connectors to receive, measure and transmit seismic reflections resulting from an energy source to data collection units, which store information for processing and analysis. In the marine environment, large ocean-going vessels tow long seismic cables known as “streamers” containing hydrophones which are used to detect pressure changes. Hydrophones transmit electrical impulses back to the vessel’s data collection unit, where the seismic data is stored for subsequent processing and analysis. Our marine seismic products help steer streamers while being towed and help recover streamers when accidents occur.

We have also developed high definition reservoir characterization products for the borehole and ocean-bottom applications. Utilizing these products, our customers can utilize seismic technologies to better identify and enhance the recovery of oil and gas deposits over the life of a reservoir.

In 1995, we modified our thermal imaging product technology that we had traditionally applied in our seismic business and were able to apply that technology to other markets. We are now manufacturing and marketing our thermal imaging products, which includes thermal imaging equipment and dry thermal film, to the screen print, point of sale, signage and textile market sectors, along with some sales to seismic customers. Our thermal imaging equipment is capable of producing data images ranging in size from 12 to 54 inches wide, with resolution ranging from 400 to 1,200 dpi.

On September 30, 2004, we acquired the thermal printhead production assets of Graphtec Corporation (for a discussion of our acquisition of assets from Graphtec, see the heading “Business—Acquisitions” in our Report on Form 10-K for our fiscal year ended September 30, 2004, incorporated by reference in this prospectus). As a result, we now own the assets and technology needed to produce the wide-format thermal printheads that we use to manufacture our wide-format thermal imaging equipment.

We have recently expanded our cable line of products beyond the seismic area and are offering the design and manufacturing of cable products to the offshore oil and gas and offshore construction industries.

Our principal executive offices are located at 7007 Pinemont Drive, Houston, Texas 77040-6601. Our telephone number at that location is (713) 986-4444. Our website is http://www.oyogeospace.com. Information contained in our website is not incorporated by reference into this prospectus and you should not consider information contained in our website as part of this prospectus.

An investment in our common stock involves a high degree of risk. For a discussion of certain matters that should be considered by prospective purchasers of our common stock offered hereby, see “Risk Factors” beginning on page 3.

An investment in our common stock involves risks. The risks described below are not the only ones facing our company. Additional risks not presently known to us or that we currently deem immaterial may also impair our business operations. Our business, financial condition, results of operations or prospects could be materially adversely affected by any of these risks. The trading price of our common stock could decline due to any of these risks, and you may lose all or part of your investment. This prospectus, including the documents it incorporates by reference, also contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those anticipated in these forward-looking statements as a result of certain factors, including the risks faced by us described below and elsewhere in this prospectus or in the documents it incorporates by reference. While we cannot identify all of the risk factors that may cause actual results to vary from our expectations, we believe the following risk factors that relate to our current and anticipated business should be considered carefully.

Demand for many of our products depends primarily on the level of worldwide oil and gas exploration activity. That activity, in turn, depends primarily on prevailing oil and gas prices and availability of seismic data. Historically, the markets for oil and gas have been volatile, and those markets are likely to continue to be volatile. Oil and gas prices are subject to wide fluctuation in response to relatively minor changes in the supply of and demand for oil and gas, market uncertainty and a variety of additional factors that are beyond our control. These factors include the level of consumer demand, weather conditions, domestic and foreign governmental regulations, price and availability of alternative fuels, political conditions and hostilities in the Middle East and other significant oil-producing regions, foreign supply of oil and gas, prices of foreign imports and overall economic conditions. A decline in the demand for our products could materially and adversely affect our results of operations and liquidity.

Our outlook is based on various macro-economic factors and our internal assessments, and actual market conditions could vary materially from those assumed. In recent years we have incurred significant expenditures to fund our research and development efforts and we intend to continue those expenditures in the future. However, research and development is by its nature speculative, and we cannot assure you that these expenditures will result in the development of new products or services or that any new products and services we have developed recently or may develop in the future will be commercially marketable or profitable to us. In particular, we have incurred substantial expenditures to develop seismic products for reservoir characterization applications. We cannot assure you that we will realize our expectations regarding market acceptance and revenues from these products and services.

Any unexpected material changes in oil and gas prices or other market trends that would impact seismic exploration activity would likely affect the forward-looking information contained in this document and could cause our stock price to decline. In addition, the oil and gas industry is extremely volatile and subject to change based on political and economic factors outside our control. For instance, our results for fiscal year 2003 and sales of traditional seismic products in particular, were adversely affected by the downturn in the industry, particularly as the industry continued to limit exploration activities and to be cautious in spending notwithstanding some recent improvements in, or some relative stabilization of, oil and gas commodity prices during such period.

Historically, the rate of new orders for our products has varied substantially from quarter to quarter. Moreover, we typically operate, and expect to continue to operate, on the basis of orders in hand for our products before we commence substantial manufacturing “runs”. Thus completion of orders, particularly large orders for deepwater reservoir characterization projects, can significantly impact the operating results and cash flow for any quarter, and results of operations for any one quarter may not be indicative of results of operations for future quarters. These periodic fluctuations in our operating results could adversely affect our stock price.

Our credit risks could increase as our customers continue to face difficult economic circumstances.

We believe, and have assumed, that our allowances for bad debts have been adequate in light of then-known circumstances. However, we cannot assure you that additional amounts attributable to uncollectible receivables and bad debt write-offs will not have a material adverse effect on our future results of operations. Many of our seismic contractor customers are not well capitalized and as a result do not always pay our invoices when due. We have in the past incurred write-offs in our accounts receivable due to customer credit problems. We have found it necessary from time to time to extend trade credit and promissory notes to long-term customers and others where some risks of non-payment exist. Although industry conditions have improved, some of our customers continue to experience liquidity difficulties, which increase those credit risks. An increase in the level of bad debts and any deterioration in our credit risk could adversely affect the price of our stock.

Our industry is characterized by rapid technological development and product obsolescence.

Our instruments and equipment are constantly undergoing rapid technological improvement. Our future success depends on our ability to continue to:

Current competitors or new market entrants may develop new technologies, products or standards that could render our products obsolete. We cannot assure you that we will be successful in developing and marketing, on a timely and cost effective basis, product enhancements or new products that respond to technological developments, that are accepted in the marketplace or that comply with new industry standards.

The markets for our products are highly competitive. Many of our existing and potential competitors have substantially greater marketing, financial and technical resources than we do. Additionally, two competitors in our seismic business segment currently offer a broader range of instruments and equipment for sale than we do and market this equipment as “packaged” data acquisition systems. We do not currently offer for sale such a complete “packaged” data acquisition system. Further, certain of our competitors offer financing arrangements to customers on terms that we may not be able to match. In addition, new competitors may enter the market and competition could intensify.

We cannot assure you that sales of our products will continue at current volumes or prices if current competitors or new market entrants introduce new products with better features, performance, price or other characteristics than our products. Competitive pressures or other factors also may result in significant price competition that could have a material adverse effect on our results of operations and on the price of our stock.

In our seismic business segment, we market our traditional products to contractors and large, independent and government-owned oil and gas companies. We estimate that, based on published industry sources, fewer than 30 seismic contracting companies are currently operating worldwide (excluding those operating in Russia and the former Soviet Union, India, the People’s Republic of China and certain Eastern European countries, where seismic data acquisition activity is difficult to verify). We estimate that fewer than ten seismic contractors are engaged in marine seismic exploration. Due to these market factors, a relatively small number of customers, some of whom are experiencing financial difficulties, have accounted for most of our sales. From time to time these seismic contractors have sought to vertically integrate and acquire our competitors, which has influenced their supplier decisions before and after such transactions. The loss of a small number of these customers could materially and adversely impact our sales, which could cause a material decline in the price of our stock.

We hold and from time to time we apply for certain patents relating to our seismic data acquisition and other products. We also own several patents which relate to the development of dry thermal film. We cannot assure you that our patents will prove enforceable, that any patents will be issued for which we have applied or that competitors will not develop functionally similar technology outside the protection of any patents we have or may obtain.

Our foreign subsidiaries and foreign marketing efforts face additional risks and difficulties.

Net sales outside the United States accounted for approximately 61% of our net sales during fiscal year 2004 and are again expected to represent a substantial portion of our net sales for fiscal year 2005 and subsequent years. Substantially all of our sales from the United States are made in U.S. dollars, but from time to time we make sales in foreign currencies and may, therefore, be subject to foreign currency fluctuations on our sales. In addition, net assets reflected on the balance sheets of our Russian, Canadian and United Kingdom subsidiaries are subject to currency fluctuations. Significant foreign currency fluctuations could adversely impact our results of operations.

Foreign sales are subject to special risks inherent in doing business outside of the United States, including the risk of war, terrorist activities, civil disturbances, embargo and government activities and foreign attitudes about conducting business activities with the United States, all of which may disrupt markets. Foreign sales are also generally subject to the risk of compliance with additional laws, including tariff regulations and import and export restrictions. Sales in certain foreign countries require prior United States government approval in the form of an export license. We cannot assure you that we will not experience difficulties in connection with future foreign sales. Also, should we experience substantial growth in certain foreign markets, for example in Russia, we may not be able to transfer cash balances to the United States to assist with debt servicing or other obligations.

We currently manufacture dry thermal film which is used by our customers in the thermal imaging equipment we manufacture using the assets we acquired from Graphtec (for a discussion of our acquisition of assets from Graphtec, see the information under the heading “Business—Acquisitions” in our Report on Form 10-K for our fiscal year ended September 30, 2004, incorporated by reference in this prospectus). We also purchase a large quantity of dry thermal film from another supplier of thermal film. Except for this other supplier, we know of no other source for dry thermal film that performs well in our thermal imaging equipment.

If we are unable to economically manufacture dry thermal film internally or if the other supplier of our thermal film were to discontinue supplying dry thermal film or were unable to supply dry thermal film in sufficient quantities to meet our requirements, our ability to compete in the thermal imaging marketplace could be severely damaged, adversely affecting our financial performance, which could cause a decline in or stock price.

OYO Corporation, a Japanese corporation, owns indirectly in the aggregate approximately 51% of our common stock. Accordingly, OYO Corporation, through OYO Corporation U.S.A., a wholly owned subsidiary of OYO Corporation, has in the past been able to elect all of our directors and to control our management, operations and affairs. Assuming OYO Corporation U.S.A. sells all of its shares in the company offered under this prospectus, it will still own approximately 26% of our common stock. Therefore, OYO Corporation, through OYO Corporation U.S.A., will continue to be our largest stockholder and could continue to exercise substantial influence over the election of our directors and therefore our operations and all matters submitted to a vote of our stockholders. It is expected that Mr. Kobayashi, a director and senior executive officer of OYO Corporation and the President of OYO Corporation U.S.A., will continue to serve as a director of the company even if OYO Corporation U.S.A. sells all of its shares in our company offered under this prospectus.

Our success depends on attracting and retaining highly skilled professionals. A number of our employees are highly skilled engineers and other professionals. If we fail to continue to attract and retain such professionals, our ability to compete in the industry could be adversely affected. In addition, our success depends to a significant extent upon the abilities and efforts of the members of our senior management.

A general downturn in the U.S. economy in future periods may adversely affect our business.

A general downturn in the U.S. economy in future periods could adversely affect our business in ways that we cannot identify. Any economic downturn may adversely affect the demand for oil and gas generally or cause volatility in oil and gas prices and, therefore, adversely affect the demand for our services to the oil and gas industry and related service industry. It could also adversely affect the demand for consumer products, which could in turn adversely affect our thermal solutions business. To the extent these factors adversely affect other seismic companies in the industry, we could see an oversupply of products and services and downward pressure on pricing for seismic products and services that would also adversely affect us.

In response to several high profile cases of accounting irregularities, the Sarbanes-Oxley Act of 2002, or “the Act,” was enacted into law on July 30, 2002. We are required to begin to comply with the annual requirements of Section 404 of the Act with respect to our internal controls over financial reporting effective with our fiscal year beginning October 1, 2005. The Act, and rules promulgated thereunder, as well as new NASDAQ listing standards addressing corporate governance issues, endeavor to provide greater accountability and promote investor confidence by imposing specific corporate governance requirements, by requiring more stringent controls and certifications by corporate management and by ultimately imposing new auditor attestations. The Act and new NASDAQ rules affect how audit committees, corporate management and auditors of publicly traded companies carry out their respective responsibilities and interact with each other and mandate composition of audit committees by independent directors. The Act will result in higher expenses for publicly traded companies as a result of higher audit and review fees, higher legal fees, higher director fees, and higher internal costs to document, test and potentially remediate internal controls. The Act, together with the financial scandals and difficult economic enviroment of recent years has also led to substantially increased premiums for director and officer liability insurance. These increased expenses will affect smaller public companies, like us, disproportionately from their effects on companies with larger revenue and operating income bases with which to absorb such increased costs.

With respect to the internal controls requirement flowing from the Act, we will devote substantial efforts and incur significant expenses in fiscal years 2005 and 2006 in documenting, testing and potentially remediating our internal controls system. We have hired outside experts to help us with respect to these matters. Notwithstanding our substantial efforts, the requirements of the Act as to internal controls are new and

significant and, to some extent, quite burdensome, and there exists a risk that we will not be able to meet all the requirements of the Act in such regard by the end of fiscal year 2006, when we are required to report on our internal controls and provide our auditor’s opinion thereon.

After this offering, we will continue to have a relatively small public float and our stock price may be volatile.

Before the sale of shares offered under this prospectus, we had approximately 2.4 million shares outstanding held by non-affiliates. Assuming the sale by the selling stockholder of all of its shares in our company offered under this prospectus, we would still only have approximately 3.8 million shares held by non-affiliates. Our small float has resulted in, and we expect that it will continue to result in, a relatively illiquid market for our common stock. Our daily trading volume during fiscal year 2004 averaged approximately 7,500 shares. While we believe that our average daily trading volume may increase following the sale by the selling stockholder of its shares in the company offered under this prospectus, we do not expect that any such increase will significantly increase the liquidity of the market for our shares. Our small float and daily trading volumes have in the past caused, and could in the future result in, greater volatility of our stock price.

All of the other facts and circumstances described in this section on “Risk Factors” could adversely affect our stock price. Many of these factors are beyond our control, and could cause the market price of our common stock to fluctuate significantly. These broad market fluctuations could result in extreme fluctuations in the price of our common stock, which could cause a decline in the value of our investors’ stock.

This prospectus contains or incorporates by reference statements concerning our future results and performance and other matters that are “forward-looking” statements within the meaning of Section 27A of the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended (the Exchange Act). These statements involve known and unknown risks, uncertainties, and other factors that may cause our or our industry’s actual results, levels of activity, performance, or achievements to be materially different from any future results, levels of activity, performance, or achievements expressed or implied by those forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “may,” “will,” “should,” “intend,” “expect,” “plan,” “anticipate,” “believe,” “estimate,” “predict,” “potential,” or “continue,” or the negative of such terms or other comparable terminology.

Examples of other forward-looking statements contained in this prospectus, including statements incorporated by reference in this prospectus, include statements regarding:

These forward-looking statements reflect our best judgment about future events and trends based on the information currently available to us. Our results of operations can be affected by the assumptions we make or by risks and uncertainties known or unknown to us, including those described under “Risk Factors.” Therefore, we cannot guarantee the accuracy of the forward-looking statements. Actual events and results of operations may vary materially from our current expectations and assumptions.

All of the shares of our common stock being offered pursuant to this prospectus are being offered by OYO Corporation U.S.A. We will not receive any proceeds from the sale of those shares.

The following is a description of our capital stock and a summary of the rights of our stockholders and provisions pertaining to indemnification of our directors and officers. You should also refer to our articles of incorporation and bylaws, which are incorporated by reference in this prospectus supplement, and to Delaware law.

Our authorized share capital consists of 20,000,000 shares of common stock, par value $.01 per share, and 1,000,000 shares of preferred stock, par value $.01 per share. As of April 21, 2005, there were 5,607,365 shares of our common stock issued and outstanding and no share of our preferred stock issued and outstanding. We have reserved a total of 1,325,000 shares of our common stock for grants of options, restricted stock awards and for issuance to our directors in partial payment of their directors’ fees, all under our stock plans. The outstanding shares of our common stock, including the shares of our common stock that are being offered by the selling stockholder hereunder, are fully paid and nonassessable.

The holders of our common stock are entitled to one vote per share in the election of directors and on all other matters on which stockholders are entitled or permitted to vote. The holders of our common stock are not entitled to vote cumulatively for the election of directors. Holders of our common stock have no redemption, conversion, preemptive or other subscription rights. The holders of our common stock are not able to act by written consent. Our bylaws provide that special meetings of our stockholders may be called only by our board of directors.

In the event of the liquidation, dissolution or winding up of OYO Geospace, holders of our common stock are entitled to share ratably in all of our assets remaining, if any, after satisfaction of our debts and liabilities and the preferential rights of the holders of the preferred stock, if any, then outstanding. The outstanding shares of our common stock, including the shares of common stock offered by the selling stockholder, are validly issued, fully paid and nonassessable.

We are subject to certain restrictions on the payment of distributions to the holders of our common stock. For a discussion on these restrictions, see the information under the heading “Market for Registrant’s Common Equity and Related Stockholder Matters” in our Report on Form 10-K for the fiscal year ended September 30, 2004, incorporated by reference in this prospectus.

Preferred stock may be issuable in one or more series from time to time at the discretion of our board of directors. Our board of directors is authorized to fix the respective designations, relative rights, preferences, qualifications, restrictions and limitations of each series. The issuance of preferred stock could be used as an “anti-takeover” device without requiring further action on the part of the holders of our common stock.

Our restated certificate of incorporation contains a provision that eliminates the personal liability of a director to the company and its stockholders for monetary damages for breach of his fiduciary duty as a director to the extent currently allowed under the Delaware General Corporation Law, or “DGCL.” If a director were to breach such duty in performing his duties as a director, neither the company nor its stockholders could recover monetary damages from the director, and the only course of action available to our stockholders would be

equitable remedies, such as an action to enjoin or rescind a transaction involving a breach of fiduciary duty. To the extent certain claims against directors are limited to equitable remedies, the provision in our restated certificate of incorporation may reduce the likelihood of derivative litigation and may discourage stockholders or management from initiating litigation against directors for breach of their fiduciary duty. Additionally, equitable remedies may not be effective in many situations. If a stockholder’s only remedy is to enjoin the completion of our board of directors’ action, the remedy would be ineffective if the stockholder does not become aware of a transaction or event until after it has been completed. In such a situation, it is possible that the stockholders and our company would have no effective remedy against the directors. Under our restated certificate of incorporation, liability for monetary damages remains for (i) any breach of the duty of loyalty to our company or its stockholders, (ii) acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) payment of an improper dividend or improper repurchase of our stock under Section 174 of the DGCL or (iv) any transaction from which the director derived an improper personal benefit. Our restated certificate of incorporation further provides that in the event the DGCL is amended to allow the further elimination or limitation of the liability of directors, then the liability of our directors shall be limited or eliminated to the fullest extent permitted by the amended DGCL.

Our restated certificate of incorporation obligates our company at all times to maintain the effectiveness of bylaw provisions providing for the mandatory indemnification of directors of our company to the maximum extent permitted by the DGCL. Under our bylaws, each person who is or was a director or officer of the company or a subsidiary of the company, or who serves or served any other enterprise or organization at the request of the company or a subsidiary of the company, shall be indemnified by the company to the full extent permitted by the DGCL.

The provisions of our restated certificate of incorporation summarized above may not be amended or repealed without the affirmative vote of 66²/3% of the voting power of all shares of our company.

Under Delaware law, to the extent that a person is successful on the merits in defense of a suit or proceeding brought against him by reason of the fact that he is or was a director or officer of our company, or serves or served any other enterprise or organization at the request of our company, he shall be indemnified against expenses (including attorneys’ fees) actually and reasonably incurred in connection with such action.

Under Delaware law, to the extent an indemnified person is not successful in defense of a third party civil suit or a criminal suit, or if such suit is settled, such person shall be indemnified against both (i) expenses, including attorneys’ fees, and (ii) judgments, fines and amounts paid in settlement if he acted in good faith and in a manner he reasonably believed to be in, or not opposed to, the best interests of the company and, with respect to any criminal action, had no reasonable cause to believe his conduct was unlawful, except that if such person is adjudged to be liable in such a suit for negligence or misconduct in the performance of his duty to the company, he cannot be made whole even for expenses unless the court determines that he is fully and reasonably entitled to indemnity for such expenses.

The company maintains insurance to protect officers and directors from certain liabilities, including liabilities against which the company cannot indemnify its directors and officers.

In addition to the foregoing, our company has entered into separate indemnification agreements with each of our directors. Pursuant to these agreements, our company has agreed to indemnify and hold each such director harmless to the fullest extent permitted by law, from any loss, damage or liability incurred in the course of his respective service as a director of the company. The amount paid by the company is reducible by the amount of insurance paid to or on behalf of such director with respect to any event giving rise to indemnification. Each director’s right to indemnification is to survive his respective death or termination as director.

Our company’s bylaws provide for the indemnification of its officers and directors and the advancement to them of expenses in connection with proceedings and claims, to the fullest extent permitted under the DGCL. Such indemnification may be made even though directors and officers may otherwise be determined later not to be entitled to indemnification under other provisions by the bylaws.

The above discussion of the DGCL and of our restated certificate of incorporation and bylaws and form of director indemnity agreement is not intended to be exhaustive and is qualified in its entirety by such statute and our restated certificate of incorporation and bylaws and the form of director indemnity agreement.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers or persons controlling our company pursuant to the foregoing provisions, the company has been informed that in the opinion of the Securities and Exchange Commission, such indemnification is against public policy as expressed in the Securities Act and is therefore unenforceable.

The transfer agent and registrar for our common stock is Computershare Trust Company, Inc.

All of the shares in the company that are being offered under this prospectus are being offered by our stockholder OYO Corporation U.S.A., which is referred to in this offering memorandum as our “selling stockholder.”

Since 1998, OYO Corporation, a Japanese corporation, through its wholly owned subsidiary OYO Corporation U.S.A., has beneficially owned 2,850,000 shares of our common stock. That represents approximately 51% of our outstanding shares. OYO Corporation U.S.A. is offering to sell 1,400,000 shares of our common stock under this prospectus. Assuming it sells all of those shares, it will own 1,450,000 shares, or approximately 26%, of our common stock.

This prospectus also covers any additional shares of common stock which become issuable in connection with the shares registered for sale hereby by reason of any stock dividend, stock split, recapitalization or other similar transaction effected without the receipt of consideration which results in an increase in the number of our outstanding shares of common stock.

Mr. Katsuhiko Kobayashi, a director of the company since 1995, is a director and senior executive officer with OYO Corporation. He has held that position since March 2001. Mr. Kobayashi is also the President of OYO Corporation U.S.A. He has held that position since May 31, 2002.

In fiscal year 2004, we purchased printheads for our thermal plotters from OYO Corporation pursuant to a Printhead Purchase Agreement that we entered into with OYO Corporation before our initial public offering. OYO Corporation in turn purchased the printheads from a Japanese supplier. For its service and assistance in these transactions, pursuant to the Printhead Purchase Agreement, OYO Corporation marked up its cost for these printheads by five percent in reselling them to us. We believe that by purchasing the printheads through OYO Corporation, we received a more favorable price for the printheads than we could have obtained had we negotiated their purchase ourselves. On September 30, 2004, we purchased the thermal printhead production assets from a Japanese corporation. As a result of this purchase, our obligations under the Printhead Purchase Agreement have been terminated, and we expect that we will no longer need to purchase printheads through OYO Corporation.

Pursuant to a Master Sales Agreement that we have entered into with OYO Corporation before our initial public offering, the company and OYO Corporation purchase products from one another at scheduled discounts of between 5 to 20 percent off the seller’s list prices. In fiscal year 2004, we sold approximately $0.5 million of products to OYO Corporation and its affiliates and we purchased approximately $0.8 million of products from OYO Corporation (including the products covered by the Printhead Purchase Agreement).

All shares of common stock being offered under this prospectus are being offered on behalf of the selling stockholder.

The shares offered by this prospectus may be sold from time to time by or for the account of the selling stockholder pursuant to this prospectus or pursuant to Rule 144 under the Securities Act of 1933. Sales of shares pursuant to this prospectus may be made on NASDAQ, in the over-the-counter market or otherwise at prices and on terms then prevailing or at prices related to the then current market price (in each case as determined by the selling stockholder). Sales may be made directly or through agents designated from time to time, or through dealers or underwriters to be designated or in negotiated transactions.

At the time a particular offer of shares is made, to the extent required by applicable law, we will add a supplement to this prospectus to disclose the following information about any particular offering:

The selling stockholder may sell shares directly to other purchasers, through agents, underwriters or through broker-dealers. Any selling agents, underwriter or broker-dealers may receive compensation in the form of underwriting discounts, concessions or commissions from the selling stockholder, from purchasers of shares for whom they act as agents, or from both sources. That compensation may be in excess of customary commissions.

The selling stockholder and any broker-dealers, agents and underwriters that participate in the distribution of the shares may be deemed to be “underwriters” within the meaning of the Securities Act of 1933 in connection with the sales. Any commissions, and any profit on the resale of shares, received by the selling stockholder and any such broker-dealers, agents or underwriters may be deemed to be underwriting discounts and commissions. We have been advised by the selling stockholder that it has not, as of the date of this prospectus, entered into any agreement with any agent, broker, dealer or underwriter for the sale of the shares, but understand that the selling stockholder has had conversations with representatives of securities firms contemplating a possible firm commitment underwriting for all of the shares covered by this prospectus.

The selling stockholder will pay all costs and expenses incurred in connection with the registration and offering of the shares under this prospectus. The selling stockholder will also be responsible for any commissions, underwriting discounts or similar charges on the sale of shares under this prospectus.

Fulbright & Jaworski L.L.P., Houston, Texas, has passed on certain legal matters with respect to the shares of common stock offered hereunder. Charles H. Still, a partner at Fulbright & Jaworski L.L.P., is a director and the secretary of the company. Any underwriters will be advised about the issues relating to the offering by their own legal counsel.

The financial statements incorporated in this prospectus by reference to the Annual Report on Form 10-K for the year ended September 30, 2004 have been so incorporated in reliance on the report of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in accounting and auditing.

We have filed with the Securities and Exchange Commission a registration statement on Form S-3 under the Securities Act with respect to the shares being offered under this prospectus. This prospectus, which is included in the registration statement, does not contain all of the information in the registration statement. For further information regarding our company and our common stock, please see the registration statement and our other filings with the SEC, including our annual, quarterly and current reports and proxy statements, which you may read and copy at the Public Reference Room maintained by the SEC at 450 Fifth Street, N.W., Washington, D.C. 20549. You may obtain information about the public reference room by calling the SEC at 1-800-SEC-0330. Our SEC filings are also available to the public on the SEC’s Internet website at http://www.sec.gov. Our Internet website address is http://www.oyogeospace.com.

We furnish holders of our common stock with annual reports containing financial statements audited by our independent auditors in accordance with generally accepted accounting principles following the end of each fiscal year. We file reports and other information with the SEC pursuant to the reporting requirements of the Exchange Act.

Our common stock is listed on NASDAQ and we are required to file reports, proxy statements and other information with NASDAQ. You may read any document we file with NASDAQ at the offices of The NASDAQ Stock Market, Inc. which is located at 9600 Blackwell Road, Rockville, MD 20850.

Descriptions in this prospectus of documents are intended to be summaries of the material, relevant portions of those documents, but may not be complete descriptions of those documents. For complete copies of those documents, please refer to the exhibits to the registration statement and other documents filed by us with the SEC.

We are incorporating the following documents, including the exhibits thereto, which we have filed with the SEC, in this prospectus by reference:

All documents we file with the SEC pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus but before the termination of the offering by this prospectus shall be deemed to be incorporated herein by reference and to be a part hereof from the date of the filing of those documents.

Any statement contained in a document incorporated by reference herein shall be deemed to be modified or superseded for all purposes to the extent that a statement contained in this prospectus, or in any other subsequently filed document which is also incorporated or deemed to be incorporated by reference, modifies or supersedes such statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this prospectus.

We will provide, without charge, to each person to whom a copy of this prospectus has been delivered, upon written or oral request of such person, a copy of any or all of the documents incorporated by reference herein (other than certain exhibits to such documents not specifically incorporated by reference). Requests for such copies should be directed to:

An estimate of the fees and expenses in connection with the issuance and distribution of the securities registered under this registration statement hereby is as follows:

The selling stockholder will pay all of the costs and expenses incurred in connection with issuance and distribution of the securities registered under this registration statement.

The provisions under the heading “Description of Capital Stock and Indemnification of Directors and Officers—Indemnification of Directors and Officers” in the prospectus is incorporated by reference herein in its entirety.

The exhibits listed in the Exhibit Index are filed as part of this Registration Statement.

(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement: (i) to include any prospectus required by Section 10(a)(3) of the Securities Act of 1933; (ii) to reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20 percent change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and (iii) to include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement; provided, however, that (i) and (ii) above do not apply if the Registration Statement is on Form S-3 or Form S-8, and the information required to be included in a post-effective amendment by (i) and (ii) is contained in periodic reports filed with or furnished to the Commission by the Registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the Registration Statement.

(2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director, officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of such issue.

The undersigned Registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the Registrant’s annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 that is incorporated by reference in the Registration Statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(1) For purposes of determining any liability under the Securities Act of 1933, the information omitted from the form of prospectus filed as part of this Registration Statement in reliance upon Rule 430A and contained in a form of prospectus filed by the Registrant pursuant to Rule 424(b)(1) or (4) or 497(h) under the Securities Act of 1933 shall be deemed to be part of this Registration Statement as of the time it was declared effective.

(2) For the purpose of determining any liability under the Securities Act of 1933, each post-effective amendment that contains a form of prospectus shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Houston, State of Texas, on April 25, 2005.


OYO GEOSPACE CORPORATION

By:		/S/ GARY D. OWENS
		Gary D. Owens Chairman of the Board, President and Chief Executive Officer

KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Gary D. Owens and Thomas T. McEntire, and each of them, as his true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution for him and in his name, place and stead, in any and all capacities, to sign any and all amendments (including any and all post-effective amendments) to this Registration Statement on Form S-3 and any registration statement for the same offering filed pursuant to Rule 462 under the Securities Act of 1933, as amended, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents or any of them, or their or his substitute or substitutes, may lawfully do or cause to be done by virtue thereof.

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated:


		Page
Prospectus Summary		1
Risk Factors		3
Forward-Looking Statements		8
Use of Proceeds		8
Description of Capital Stock and Indemnification of Directors and Officers		9
Selling Stockholder		11
Plan of Distribution		12
Legal Matters		13
Experts		13
Where You Can Find More Information		13
Incorporation of Certain Information by Reference		14


SEC registration fee	$	3,137
Transfer Agent fees		5,000
Legal fees and expenses		150,000
Accounting fees and expenses		50,000
Printing and mailing expenses		25,000
Miscellaneous expenses		20,000
Total	$	253,137


Exhibit Number		Description
4.1		Specimen Certificate for shares of Common Stock (incorporated by reference from Exhibit 4.1 to the Company’s Registration Statement on Form S-1 filed with the SEC on September 30, 1997 (Registration No. 333-36727)).

4.2		Restated Certificate of Incorporation of OYO Geospace Corporation (incorporated by reference from Exhibit 3.1 to the Company’s Registration Statement on Form S-1 filed with the SEC on September 30, 1997 (Registration No. 333-36727)).

4.3		Restated Bylaws of OYO Geospace Corporation (incorporated by reference from Exhibit 3.2 to the Company’s Registration Statement on Form S-1 filed with the SEC on September 30, 1997 (Registration No. 333-36727)).

4.4		Form of Director Indemnity Agreement (incorporated by reference from Exhibit 10.7 to Amendment No. 2 to the Company’s Registration Statement on Form S-1 filed with the SEC on November 18, 1997 (Registration No. 333-36727))

**5.1		Opinion of Fulbright & Jaworski L.L.P.

*23.1		Consent of PricewaterhouseCoopers LLP.

**23.2		Consent of Fulbright & Jaworski L.L.P. (incorporated by reference from Exhibit 5.1).

*24.1		Power of Attorney (included in Signature Page).


Exhibit Number		Description
4.1		Specimen Certificate for shares of Common Stock (incorporated by reference from Exhibit 4.1 to the Company’s Registration Statement on Form S-1 filed with the SEC on September 30, 1997 (Registration No. 333-36727)).

4.2		Restated Certificate of Incorporation of OYO Geospace Corporation (incorporated by reference from Exhibit 3.1 to the Company’s Registration Statement on Form S-1 filed with the SEC on September 30, 1997 (Registration No. 333-36727)).

4.3		Restated Bylaws of OYO Geospace Corporation (incorporated by reference from Exhibit 3.2 to the Company’s Registration Statement on Form S-1 filed with the SEC on September 30, 1997 (Registration No. 333-36727)).

4.4		Form of Director Indemnity Agreement (incorporated by reference from Exhibit 10.7 to Amendment No. 2 to the Company’s Registration Statement on Form S-1 filed with the SEC on November 18, 1997 (Registration No. 333-36727))

**5.1		Opinion of Fulbright & Jaworski L.L.P.

*23.1		Consent of PricewaterhouseCoopers LLP.

**23.2		Consent of Fulbright & Jaworski L.L.P. (incorporated by reference from Exhibit 5.1).

*24.1		Power of Attorney (included in Signature Page).

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents

Table of Contents


Signature	Title	Date

/s/ GARY D. OWENS Gary D. Owens	Chairman of the Board, President, Chief Executive Officer (Principal Executive Officer), and Director	April 25, 2005

/s/ THOMAS T. MCENTIRE Thomas T. McEntire	Chief Financial Officer (Principal Financial and Accounting Officer)	April 25, 2005

/s/ WILLIAM H. MOODY William H. Moody	Director	April 25, 2005

/s/ KATSUHIKO KOBAYASHI Katsuhiko Kobayashi	Director	April 25, 2005

/s/ RYUZO OKUTO Ryuzo Okuto	Director	April 25, 2005

/s/ THOMAS L. DAVIS Thomas L. Davis	Director	April 25, 2005

/s/ MICHAEL J. SHEEN Michael J. Sheen	Director	April 25, 2005

/s/ CHARLES H. STILL Charles H. Still	Director	April 25, 2005