Stockholders' Equity

3 Months Ended

Mar. 31, 2014

Stockholders' Equity Note [Abstract]

Stockholders' Equity Note Disclosure [Text Block]

9. Stockholders’ Equity

Significant Changes in Stockholders’ Equity

During the three months ended March 31, 2014, additional paid-in capital increased by $3.6 million. $3.5 million of this increase is attributable to (i) $1.0 million in proceeds received from the exercise of warrants to purchase a total of 800,000 shares of the Company’s common stock and (ii) $2.5 million being the fair value of these warrants reclassified from liabilities. See Note 10 below for additional information.

Shelf Registration

        On May 15, 2012, the Company filed a Shelf Registration which was declared effective by the SEC on May 21, 2012. The Shelf Registration permits the Company to sell, from time to time, up to an aggregate of $50.0 million of various securities, including common stock, preferred stock, warrants to purchase common stock or preferred stock and units consisting of one or more shares of common stock, shares of preferred stock, warrants, or any combination of such securities. However, the Company may not sell its securities in a primary offering pursuant to the Shelf Registration or any other registration statement on Form S-3 with a value exceeding one-third of its public float in any 12-month period (unless the Company’s public float rises to $75.0 million or more). The Shelf Registration is intended to provide the Company with additional flexibility to access capital markets for general corporate purposes, subject to market conditions and the Company's capital needs.

        On July 3, 2013, the Company closed a public offering made pursuant to the Company’s Shelf Registration in which it sold 1,730,000 units consisting of one share of common stock and on half of a warrant to purchase one share of common stock for a price of $1.25 per unit. The Company received gross proceeds of $2.2 million and net proceeds of approximately $1.7 million after deducting discounts and commissions to the Underwriter and offering expenses.

        On April 4, 2014, Clean Diesel Technologies, Inc. closed a registered direct offering of 2,030,000 shares of common stock and warrants to purchase 812,000 shares of common stock. The Company received net proceeds of approximately $6.1 million after deducting placement agent fees and other estimated offering expenses. See Note 15 for further discussion.

        Common Stock Purchase Agreement with LPC

        On October 7, 2011, the Company signed a Purchase Agreement with LPC, together with a Registration Rights Agreement, whereby LPC agreed to purchase up to $10.0 million of the Company’s common stock over a 30-month period ending April 24, 2014. This expired unused in April 2014.