Document:

EX-4.1

 Exhibit 4.1 

FORM OF WARRANT 
 CLEAN
DIESEL TECHNOLOGIES, INC. 
 Warrant To Purchase Common Stock 

Warrant No.: 
 Number of Shares of Common
Stock:                 
 Date of Issuance: April 4, 2014
(“Issuance Date”) 
 Clean Diesel Technologies, Inc., a corporation existing under the laws of Delaware (the
“Company”), hereby certifies that, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged,
                    , the registered holder hereof or its permitted assigns (the “Holder”), is entitled, subject to the terms set
forth below, to purchase from the Company, at the Exercise Price (as defined below) then in effect, upon exercise of this Warrant to Purchase Common Stock (including any Warrants to Purchase Common Stock issued in exchange, transfer or replacement
hereof, the “Warrant”), at any time or times after the date occurring six months after the Issuance Date, but not after 11:59 p.m., New York time, on the Expiration Date, (as defined below),
                     (                    ) fully
paid nonassessable shares of Common Stock, subject to adjustment as provided herein (the “Warrant Shares”). Except as otherwise defined herein, capitalized terms in this Warrant, shall have the meanings set forth in Section 14.
This Warrant is one of the Warrants (the “Warrants”) issued pursuant to (i) the Company’s Registration Statement on Form S-3, (File number 333-181443) (the “Registration Statement”) and (ii) the
Company’s prospectus supplement dated as of April 1, 2014. 
 1. EXERCISE OF WARRANT. 

(a) Mechanics of Exercise. Subject to the terms and conditions hereof (including, without limitation, the limitations set forth in
Section 1(f)), this Warrant may be exercised by the Holder at any time and from time to time after the date occurring six months after the Issuance Date and on or before the Expiration Date, in whole or in part, by (i) delivery of a
written notice, in the form attached hereto as Exhibit A (the “Exercise Notice”), of the Holder’s election to exercise this Warrant and (ii) (A) payment to the Company of an amount equal to the applicable
Exercise Price multiplied by the number of Warrant Shares as to which this Warrant is being exercised (the “Aggregate Exercise Price”) in cash or by wire transfer of immediately available funds or (B) only in the circumstances
set forth in Section 1(d), by notifying the Company that this Warrant is being exercised pursuant to a Cashless Exercise (as defined in Section 1(d)). The Holder shall not be required to deliver the original Warrant in order to effect an
exercise hereunder. Execution and delivery of the Exercise Notice with respect to less than all of the Warrant Shares shall have the same effect as cancellation of the original Warrant and issuance of a new Warrant evidencing the right to purchase
the remaining number of Warrant Shares. On or before the first (1st) Trading Day following the date on which the Company has received the Exercise Notice, the Company shall transmit by facsimile an acknowledgment of confirmation of receipt of
the Exercise Notice to the Holder and the transfer agent with respect to the Company’s Common Stock (the “Transfer Agent”). On or before the 

 
third (3rd) Trading Day following the date on which the Company has received the Exercise Notice, so long as the Holder delivers the Aggregate Exercise Price (or in the circumstances set
forth in Section 1(d), notice of a Cashless Exercise) on or prior to the second (2nd) Trading Day following the date on which the Company has received the Exercise Notice (the “Share Delivery Date”) (provided that if the
Aggregate Exercise Price has not been delivered by such date, the Share Delivery Date shall be one (1) Trading Day after the Aggregate Exercise Price is delivered), the Company shall (X) provided that the Transfer Agent is participating in
The Depository Trust Company (“DTC”) Fast Automated Securities Transfer Program, upon the request of the Holder, credit such aggregate number of Warrant Shares to which the Holder is entitled pursuant to such exercise to the
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 the address as specified in the Exercise Notice, a certificate, registered in the Company’s share register in the name of the Holder or its designee, for the number of Common Stock to which the Holder is entitled pursuant
to such exercise. The Company shall be responsible for all fees and expenses of the Transfer Agent and all fees and expenses with respect to the issuance of Warrant Shares via DTC, if any. If this Warrant is submitted in connection with any exercise
pursuant to this Section 1(a) and the number of Warrant Shares represented by this Warrant submitted for exercise is greater than the number of Warrant Shares being acquired upon an exercise, then the Company shall as soon as practicable and in
no event later than three (3) Trading Days after any exercise and at its own expense, issue a new Warrant (in accordance with Section 5(d)) representing the right to purchase the number of Warrant Shares issuable immediately prior to such
exercise under this Warrant, less the number of Warrant Shares with respect to which this Warrant is exercised. No fractional Common Stock are to be issued upon the exercise of this Warrant. The Company shall pay any and all issue or transfer taxes,
withholding taxes, or other incidental tax which may be payable with respect to the issuance and delivery of Warrant Shares upon exercise of this Warrant; provided, however, that the Company shall not be required to pay any tax that may be payable
in respect of any transfer involved in the registration of any certificates for Warrant Shares or Warrants in a name other than that of the Holder. The Holder shall be responsible for all other tax liability that may arise as a result of holding or
transferring this Warrant or receiving Warrant Shares upon exercise hereof. After this Warrant has been exercised in full, the Holder shall undertake to promptly deliver the original Warrant to the Company for cancellation. 

(b) Exercise Price. For purposes of this Warrant, “Exercise Price” means $4.20, subject to adjustment as provided
herein. 
 (c) Company’s Failure to Timely Deliver Securities. If the Company shall fail to issue to the Holder on or prior to
the Share Delivery Date, a certificate for the number of Common Stock to which the Holder is entitled and register such Common Stock on the Company’s share register or to credit the Holder’s balance account with DTC for such number of
Common Stock to which the Holder is entitled upon the Holder’s exercise of this Warrant or pursuant to the Company’s obligation pursuant to clause (ii) below, and if on or after such Trading Day the Holder purchases (in an open market
transaction or otherwise) Common Stock to deliver in satisfaction of a sale by the Holder of Common Stock issuable upon such exercise that the Holder anticipated receiving from the Company (a “Buy-In”), then the Company shall,
within three (3) Trading Days after the Holder’s request and in the Holder’s discretion, either (i) 

 
pay cash to the Holder in an amount equal to the Holder’s total purchase price (including brokerage commissions, if any) for the Common Stock so purchased (the “Buy-In
Price”), at which point the Company’s obligation to deliver such certificate (and to issue such Common Stock) or credit such Holder’s balance account with DTC shall terminate, or (ii) promptly honor its obligation to deliver
to the Holder a certificate or certificates representing such Common Stock or credit such Holder’s balance account with DTC and pay cash to the Holder in an amount equal to the excess (if any) of the Buy-In Price over the product of
(A) such number of Common Stock, times (B) the Closing Bid Price on the date of exercise. Nothing shall limit the Holder’s right to pursue any other remedies available to it hereunder, at law or in equity, including, without
limitation, a decree of specific performance and/or injunctive relief with respect to the Company’s failure to timely deliver certificates representing Common Stock (or to electronically deliver such Common Stock) upon the exercise of this
Warrant as required pursuant to the terms hereof. 
 (d) Cashless Exercise. Notwithstanding anything contained herein to the
contrary, if and only if the Registration Statement covering the issuance of the Warrant Shares that are subject to the Exercise Notice is not available for the issuance of such Warrant Shares and the issuance of the Warrant Shares cannot be made
pursuant to another effective registration statement under the 1933 Act on or prior to the Share Delivery Date, the Holder may exercise this Warrant in whole or in part and, in lieu of making the cash payment otherwise contemplated to be made to the
Company upon such exercise in payment of the Aggregate Exercise Price, elect instead to receive upon such exercise the “Net Number” of shares of Common Stock determined according to the following formula (a “Cashless
Exercise”): 
  

					
	Net Number	 	=	  	(A x B) - (A x C)
		 		  	B
	
	For purposes of the foregoing formula:

  

					
	A	 	=	 	the total number of shares with respect to which this Warrant is then being exercised.
		 		 	the arithmetic average of the Closing Sale Prices of the Common Stock for the five (5)
	B	 	=	 	consecutive Trading Days ending on the date immediately preceding the date of the Exercise Notice.
	C	 	=	 	the Exercise Price then in effect for the applicable Warrant Shares at the time of such exercise.

 For purposes of Rule 144(d) promulgated under the Securities Act, as in effect on the date hereof, assuming
the Holder is not an affiliate of the Company, it is intended that the Warrant Shares issued in a Cashless Exercise shall be deemed to have been acquired by the Holder, and the holding period for the Warrant Shares shall be deemed to have commenced,
on the date this Warrant was originally issued pursuant to the Subscription Agreement. 
 (e) Disputes. In the case of a dispute as
to the determination of the Exercise Price or the arithmetic calculation of the Warrant Shares, the Company shall promptly issue to the Holder the number of Warrant Shares that are not disputed and resolve such dispute in accordance with
Section 10. 

 (f) Beneficial Ownership Limitation on Exercises. The Company shall not effect the
exercise of any portion of this Warrant, and the Holder shall not have the right to exercise any portion of this Warrant, to the extent that after giving effect to such exercise, the Holder (together with the Holder’s affiliates, and any
Persons acting as a group together with the Holder or any Holder’s affiliates) would beneficially own in excess of 4.99% (the “Maximum Percentage”) of the Common Stock outstanding immediately after giving effect to such
exercise. For purposes of the foregoing sentence, the aggregate number of shares of Common Stock beneficially owned by such Person and its affiliates shall include the number of shares of Common Stock issuable upon exercise of this Warrant with
respect to which the determination of such sentence is being made, but shall exclude shares of Common Stock which would be issuable upon (i) exercise of the remaining, unexercised portion of this Warrant beneficially owned by such Person and
its affiliates and (ii) exercise or conversion of the unexercised or unconverted portion of any other securities of the Company beneficially owned by such Person and its affiliates (including, without limitation, any convertible notes or
convertible preferred stock or warrants) subject to a limitation on conversion or exercise analogous to the limitation contained herein beneficially owned by the Holder or any of its affiliates. Except as set forth in the preceding sentence, for
purposes of this paragraph, beneficial ownership shall be calculated in accordance with Section 13(d) of the 1934 Act. To the extent that the limitation contained in this Section 1(f) applies, the Holder’s submission of an Exercise
Notice shall be deemed to be the Holder’s determination of whether this Warrant is exercisable (in relation to any other securities owned by the Holder together with any affiliates) and of which portion of this Warrant is exercisable, in each
case subject to the Maximum Percentage, and the Company shall have no obligation to verify or confirm the accuracy of such determination. In addition, a determination as to any group status as contemplated above shall be determined in accordance
with Section 13(d) of the Exchange Act and the rules and regulations promulgated thereunder. For purposes of this Warrant, in determining the number of outstanding shares of Common Stock, the Holder may rely on the number of outstanding shares
of Common Stock as reflected in the most recent of (1) the Company’s most recent Form 10-K, Form 10-Q, Current Report on Form 8-K or other public filing with the Securities and Exchange Commission, as the case may be, (2) a more
recent public announcement by the Company or (3) any other notice by the Company or the Transfer Agent setting forth the number of shares of Common Stock outstanding. For any reason at any time, upon the written or oral request of the Holder,
the Company shall within three (3) Trading Days confirm to the Holder the number of shares of Common Stock then outstanding. In any case, the number of outstanding shares of Common Stock shall be determined after giving effect to the conversion
or exercise of securities of the Company, including this Warrant, by the Holder and its affiliates since the date as of which such number of outstanding shares of Common Stock was reported. By written notice to the Company, the Holder may from time
to time increase or decrease the Maximum Percentage to any other percentage not in excess of 9.99% of the number of shares of the Common Stock outstanding immediately after giving effect to the issuance of shares of Common Stock upon exercise of
this Warrant held by the Holder and the provisions of this Section 1(f) shall continue to apply; provided that (i) any such increase will not be effective until the sixty-first (61st) day after such notice is delivered to the Company,
and (ii) any such increase or decrease will apply only to the Holder. For purposes of clarity, the Common Stock underlying this Warrant in excess of the Maximum Percentage shall not be deemed to be beneficially owned by the Holder for any
purpose including for purposes of Section 13(d) or Rule 16a-1(a)(1) of the 1934 Act. The provisions of this paragraph shall be 

 
construed and implemented in a manner otherwise than in strict conformity with the terms of this Section 1(f) to the extent necessary to correct this paragraph (or any portion hereof) which
may be defective or inconsistent with the intended beneficial ownership limitation herein contained or to make changes or supplements necessary or desirable to properly give effect to such limitation. 

2. CERTAIN ADJUSTMENTS The Exercise Price and the number of Warrant Shares are subject to adjustment from time to time as follows: 

(a) Stock Dividends and Splits. If the Company, at any time while this Warrant is outstanding, (i) pays a stock dividend on its
Common Stock or otherwise makes a distribution on any class of capital stock that is payable in shares of Common Stock, (ii) subdivides outstanding shares of Common Stock into a larger number of shares, or (iii) combines outstanding shares
of Common Stock into a smaller number of shares, then in each such case the Exercise Price shall be adjusted by multiplying the Exercise Price by a fraction of which the numerator shall be the number of shares of Common Stock outstanding immediately
before such event and of which the denominator shall be the number of shares of Common Stock outstanding immediately after such event. Any adjustment made pursuant to clause (i) of this paragraph shall become effective immediately after the
record date for the determination of stockholders entitled to receive such dividend or distribution, and any adjustment pursuant to clause (ii) or (iii) of this paragraph shall become effective immediately after the effective date of such
subdivision or combination. 
 (b) Pro Rata Distribution. If the Company, at any time while this Warrant is outstanding, distributes
to all holders of Common Stock for no consideration (i) evidences of its indebtedness, (ii) any security (other than a distribution of Common Stock covered by the preceding paragraph), (iii) rights or warrants to subscribe for or
purchase any security, or (iv) any other asset (including cash) (in each case, “Distributed Property”), then the Holder shall receive with respect to all Warrant Shares the Distributed Property that such Holder would have been
entitled to receive in respect of such number of Warrant Shares had the Holder been the record holder of such Warrant Shares immediately prior to the record date for such Distributed Property. 

(c) Fundamental Transactions. If, at any time while this Warrant is outstanding (i) the Company effects any merger or
consolidation of the Company with or into another Person, (ii) the Company effects any sale of all or substantially all of its assets in one or a series of related transactions (which shall not include the sale of its ECS division or catalyst
division or components thereof), (iii) any tender offer or exchange offer (whether by the Company or another Person) is completed pursuant to which holders of a majority of the outstanding shares of Common Stock tender or exchange their shares
for other securities, cash or property, (iv) the Company effects any reclassification of its outstanding Common Stock or any compulsory share exchange pursuant to which outstanding Common Stock is effectively converted into or exchanged for
other securities, cash or property or (v) any transaction is consummated whereby any Person or entity acquires more than 50% of the Company’s outstanding Common Stock (each, a “Fundamental Transaction”), then the Holder
shall have the right thereafter to receive, upon any subsequent exercise of this Warrant the same amount and kind of securities, cash or other property as it would have been entitled to receive upon the occurrence of such Fundamental Transaction if
it had been immediately prior to such 

 
Fundamental Transaction, the holder of the number of Warrant Shares then issuable upon exercise in full of this Warrant (the “Alternate Consideration”). The Company shall not
effect any such Fundamental Transaction unless prior to or simultaneously with the consummation thereof, any successor to the Company, surviving entity or the corporation purchasing or otherwise acquiring such assets or other appropriate corporation
or entity shall assume the obligation to deliver to the Holder, such Alternate Consideration as, in accordance with the foregoing provisions, the Holder may be entitled to purchase, and the other obligations under this Warrant. Notwithstanding
anything to the contrary, in the event of a Fundamental Transaction, the Company or any successor entity shall pay in exchange for this Warrant at the Holder’s option, exercisable at any time concurrently with or within 90 days after the
consummation of the Fundamental Transaction and amount of cash equal to the Black Scholes Value of this Warrant on the date of such Fundamental Transaction. The provisions of this paragraph (b) shall similarly apply to subsequent Fundamental
Transactions. 
 3. NONCIRCUMVENTION. The Company hereby covenants and agrees that the Company will not, by amendment of its
Certificate of Incorporation or Bylaws, or through any reorganization, transfer of assets, consolidation, merger, scheme of arrangement, dissolution, issue or sale of securities, or any other voluntary action, avoid or seek to avoid the observance
or performance of any of the terms of this Warrant, and will at all times in good faith carry out all the provisions of this Warrant and take all action as may be required to protect the rights of the Holder. Without limiting the generality of the
foregoing, the Company (i) shall not increase the par value of any Common Stock receivable upon the exercise of this Warrant above the Exercise Price then in effect, (ii) shall take all such actions as may be necessary or appropriate in
order that the Company may validly and legally issue fully paid and nonassessable shares of Common Stock upon the exercise of this Warrant, and (iii) shall, so long as any of the Warrants are outstanding, take all action necessary to reserve
and keep available out of its authorized and unissued Common Stock, solely for the purpose of effecting the exercise of the Warrants, 100% of the number of Common Stock as shall from time to time be necessary to effect the exercise of the Warrants
then outstanding (without regard to any limitations on exercise). 
 4. WARRANT HOLDER NOT DEEMED A SHAREHOLDER. Except as otherwise
specifically provided herein, the Holder, solely in such Person’s capacity as a holder of this Warrant, shall not be entitled to vote or receive dividends or be deemed the holder of share capital of the Company for any purpose, nor shall
anything contained in this Warrant be construed to confer upon the Holder, solely in such Person’s capacity as the Holder of this Warrant, any of the rights of a shareholder of the Company or any right to vote, give or withhold consent to any
corporate action (whether any reorganization, issue of stock, reclassification of stock, consolidation, merger, conveyance or otherwise), receive notice of meetings, receive dividends or subscription rights, or otherwise, prior to the issuance to
the Holder of the Warrant Shares which such Person is then entitled to receive upon the due exercise of this Warrant. In addition, nothing contained in this Warrant shall be construed as imposing any liabilities on the Holder to purchase any
securities (upon exercise of this Warrant or otherwise) or as a shareholder of the Company, whether such liabilities are asserted by the Company or by creditors of the Company. 

 5. REISSUANCE OF WARRANTS. 

(a) Transfer of Warrant. If this Warrant is to be transferred, the Holder shall surrender this Warrant to the Company, whereupon the
Company will forthwith issue and deliver upon the order of the Holder a new Warrant (in accordance with Section 5(d)), registered as the Holder may request, representing the right to purchase the number of Warrant Shares being transferred by
the Holder and, if less than the total number of Warrant Shares then underlying this Warrant is being transferred, a new Warrant (in accordance with Section 5(d)) to the Holder representing the right to purchase the number of Warrant Shares not
being transferred. 
 (b) Lost, Stolen or Mutilated Warrant. Upon receipt by the Company of evidence reasonably satisfactory to the
Company of the loss, theft, destruction or mutilation of this Warrant, and, in the case of loss, theft or destruction, of any indemnification undertaking by the Holder to the Company in customary form and, in the case of mutilation, upon surrender
and cancellation of this Warrant, the Company shall execute and deliver to the Holder a new Warrant (in accordance with Section 7(d)) representing the right to purchase the Warrant Shares then underlying this Warrant. 

(c) Exchangeable for Multiple Warrants. This Warrant is exchangeable, upon the surrender hereof by the Holder at the principal office
of the Company, for a new Warrant or Warrants (in accordance with Section 5(d)) representing in the aggregate the right to purchase the number of Warrant Shares then underlying this Warrant, and each such new Warrant will represent the right to
purchase such portion of such Warrant Shares as is designated by the Holder at the time of such surrender. 
 (d) Issuance of New
Warrants. Whenever the Company is required to issue a new Warrant pursuant to the terms of this Warrant, such new Warrant (i) shall be of like tenor with this Warrant, (ii) shall represent, as indicated on the face of such new Warrant,
the right to purchase the Warrant Shares then underlying this Warrant (or in the case of a new Warrant being issued pursuant to Section 5(a) or Section 5(c), the Warrant Shares designated by the Holder which, when added to the number of
Common Stock underlying the other new Warrants issued in connection with such issuance, does not exceed the number of Warrant Shares then underlying this Warrant), (iii) shall have an issuance date, as indicated on the face of such new Warrant
which is the same as the Issuance Date, and (iv) shall have the same rights and conditions as this Warrant. 
 6. NOTICES.
Whenever notice is required to be given under this Warrant, such notice shall be given in accordance with the provisions of the subscription agreement (the “Subscription Agreement”) dated April 1, 2014 between the Company and
the Holder with respect to the issuance of this Warrant, or to such other address, facsimile number and/or e-mail address and/or to the attention of such other Person as the recipient party has specified by written notice given to each other party
five (5) days prior to the effectiveness of such change. The Company shall provide the Holder with prompt written notice of all actions taken pursuant to this Warrant, including in reasonable detail a description of such action and the reason
therefor. Without limiting the generality of the foregoing, the Company will give written notice to the Holder (i) immediately upon any adjustment of the Exercise Price, setting forth in reasonable detail, and certifying, the calculation of
such adjustment, (ii) at least fifteen (15) days prior to the date on which the Company closes its books or takes a record (A) with respect to any dividend or distribution upon the Common Stock, (B) with respect to any grants,
issuances or sales of any 

 
Options, Convertible Securities or rights to purchase stock, warrants, securities or other property to holders of Common Stock or (C) for determining rights to vote with respect to any
Fundamental Transaction, dissolution or liquidation and (iii) at least ten (10) Trading Days prior to the consummation of any Fundamental Transaction; provided in each case that such information shall be made known to the public
prior to or in conjunction with such notice being provided to the Holder. It is expressly understood and agreed that the time of execution specified by the Holder in each Exercise Notice shall be definitive and may not be disputed or challenged by
the Company. 
 7. AMENDMENT AND WAIVER. Except as otherwise provided herein, the provisions of this Warrant may be amended and the
Company may take any action herein prohibited, or omit to perform any act herein required to be performed by it, only if the Company has obtained the written consent of the Holder. 

8. GOVERNING LAW. This Warrant shall be governed by and construed and enforced in accordance with, and all questions concerning the
construction, validity, interpretation and performance of this Warrant shall be governed by, the internal laws of the State of New York, without giving effect to any choice of law or conflict of law provision or rule (whether of the State of New
York or any other jurisdictions) that would cause the application of the laws of any jurisdictions other than the State of New York. Each party hereby irrevocably submits to the exclusive jurisdiction of the state and federal courts sitting in The
City of New York, Borough of Manhattan, for the adjudication of any dispute hereunder or in connection herewith or with any transaction contemplated hereby or discussed herein (whether brought against a party hereto or its respective affiliates,
employees or agents), and hereby irrevocably waives, and agrees not to assert in any suit, action or proceeding, any claim that it is not personally subject to the jurisdiction of any such court, that such suit, action or proceeding is brought in an
inconvenient forum or that the venue of such suit, action or proceeding is improper. Each party hereby irrevocably waives personal service of process and consents to process being served in any such suit, action or proceeding by mailing a copy
thereof to such party at the address in effective for notices to it under this Warrant and agrees that such service shall constitute good and sufficient service of process and notice thereof. Nothing contained herein shall be deemed to limit in any
way any right to serve process in any manner permitted by law. EACH PARTY HEREBY IRREVOCABLY WAIVES ANY RIGHT IT MAY HAVE, AND AGREES NOT TO REQUEST, A JURY TRIAL FOR THE ADJUDICATION OF ANY DISPUTE HEREUNDER OR IN CONNECTION WITH OR ARISING OUT
OF THIS WARRANT OR ANY TRANSACTION CONTEMPLATED HEREBY. 
 9. CONSTRUCTION; HEADINGS. This Warrant shall be deemed to be jointly
drafted by the Company and all the initial Holders of the Warrants and shall not be construed against any Person as the drafter hereof. The headings of this Warrant are for convenience of reference and shall not form part of, or affect the
interpretation of, this Warrant. 
 10. DISPUTE RESOLUTION. In the case of a dispute as to the determination of the Exercise Price,
the Closing Sale Price, the Weighted Average Price or fair market value or the arithmetic calculation of the Warrant Shares (as the case may be), the Company or the Holder (as the case may be) shall submit the disputed determinations or arithmetic
calculations (as the case may be) via facsimile (i) within two (2) Business Days after receipt of the applicable notice 

 
giving rise to such dispute to the Company or the Holder (as the case may be) or (ii) if no notice gave rise to such dispute, at any time after the Holder learned of the circumstances giving
rise to such dispute. If the Holder and the Company are unable to agree upon such determination or calculation (as the case may be) of the Exercise Price, the Closing Sale Price, the Weighted Average Price or fair market value or the number of
Warrant Shares (as the case may be) within three (3) Business Days of such disputed determination or arithmetic calculation being submitted to the Company or the Holder (as the case may be), then the Company shall, within two (2) Business
Days submit via facsimile (a) the disputed determination of the Exercise Price, the Closing Sale Price, the Weighted Average Price or fair market value (as the case may be) to an independent, reputable investment bank jointly selected by the
Company and the Holder or (b) the disputed arithmetic calculation of the Warrant Shares to the Company’s independent, outside accountant. The Company shall cause at its expense the investment bank or the accountant (as the case may be)
shall perform the determinations or calculations (as the case may be) and notify the Company and the Holder of the results no later than ten (10) Business Days from the time it receives such disputed determinations or calculations (as the case
may be). Such investment bank’s or accountant’s determination or calculation (as the case may be) shall be binding upon all parties absent demonstrable error. 

11. REMEDIES, CHARACTERIZATION AND OTHER OBLIGATIONS. The remedies provided in this Warrant shall be cumulative and in addition to all
other remedies available under this Warrant, at law or in equity (including a decree of specific performance and/or other injunctive relief), and nothing herein shall limit the right of the parties to pursue actual damages for any failure by the
other party to comply with the terms of this Warrant. The issuance of shares and/or certificates for shares as contemplated hereby upon the exercise of this Warrant shall be made without charge to the Holder or such shares for any issuance tax or
other costs in respect thereof, provided that the Company shall not be required to pay any tax which may be payable in respect of any transfer involved in the issuance and delivery of any certificate in a name other than the Holder or its agent on
its behalf. 
 12. TRANSFER. This Warrant may be offered for sale, sold, transferred or assigned without the consent of the Company.

 13. SEVERABILITY. If any provision of this Warrant is prohibited by law or otherwise determined to be invalid or unenforceable by
a court of competent jurisdiction, the provision that would otherwise be prohibited, invalid or unenforceable shall be deemed amended to apply to the broadest extent that it would be valid and enforceable, and the invalidity or unenforceability of
such provision shall not affect the validity of the remaining provisions of this Warrant so long as this Warrant as so modified continues to express, without material change, the original intentions of the parties as to the subject matter hereof and
the prohibited nature, invalidity or unenforceability of the provision(s) in question does not substantially impair the respective expectations or reciprocal obligations of the parties or the practical realization of the benefits that would
otherwise be conferred upon the parties. The parties will endeavor in good faith negotiations to replace the prohibited, invalid or unenforceable provision(s) with a valid provision(s), the effect of which comes as close as possible to that of the
prohibited, invalid or unenforceable provision(s). 

 14. CERTAIN DEFINITIONS. For purposes of this Warrant, the following terms shall have the
following meanings: 
 (a) “1933 Act” means the Securities Act of 1933, as amended. 

(b) “1934 Act” means the Securities Exchange Act of 1934, as amended. 

(c) “Black Scholes Value” means the value of this Warrant based on the Black and Scholes Option Pricing Model obtained from
the “OV” function on Bloomberg determined as of the day immediately following the public announcement of the applicable Fundamental Transaction for pricing purposes and reflecting (i) a risk-free interest rate corresponding to the
U.S. Treasury rate for a period equal to the remaining term of this Warrant as of the public announcement of a Fundamental Transaction, (ii) an expected volatility equal to the greater of 90% and the 100 day volatility obtained from the HVT
function on Bloomberg as of the day immediately following the public announcement of the applicable Fundamental Transaction, and (iii) the underlying price per share used in such calculation shall be the sum of the price per share being offered
in cash, if any, plus the value of any non-cash consideration, if any, being offered in the Fundamental Transaction. 
 (d)
“Bloomberg” means Bloomberg Financial Markets. 
 (e) “Business Day” means any day other than Saturday,
Sunday or other day on which commercial banks in The City of New York are authorized or required by law to remain closed. 
 (f)
“Closing Bid Price” and “Closing Sale Price” means, for any security as of any date, the last closing bid price and last closing trade price, respectively, for such security on the Principal Market, as reported by
Bloomberg, or, if the Principal Market begins to operate on an extended hours basis and does not designate the closing bid price or the closing trade price, as the case may be, then the last bid price or the last trade price, respectively, of such
security prior to 4:00:00 p.m., New York time, as reported by Bloomberg, or, if the Principal Market is not the principal securities exchange or trading market for such security, the last closing bid price or last trade price, respectively, of such
security on the principal securities exchange or trading market where such security is listed or traded as reported by Bloomberg, or if the foregoing do not apply, the last closing bid price or last trade price, respectively, of such security in the
over-the-counter market on the electronic bulletin board for such security as reported by Bloomberg, or, if no closing bid price or last trade price, respectively, is reported for such security by Bloomberg, the average of the bid prices, or the ask
prices, respectively, of any market makers for such security as reported in the OTC Link or “pink sheets” by OTC Markets Group Inc. (formerly Pink OTC Markets Inc.). If the Closing Bid Price or the Closing Sale Price cannot be calculated
for a security on a particular date on any of the foregoing bases, the Closing Bid Price or the Closing Sale Price, as the case may be, of such security on such date shall be the fair market value as mutually determined by the Company and the
Holder. If the Company and the Holder are unable to agree upon the fair market value of such security, then such dispute shall be resolved pursuant to Section 10. All such determinations to be appropriately adjusted for any stock dividend,
stock split, stock combination or other similar transaction during the applicable calculation period. 

 (g) “Common Stock” means (i) the Company’s Common Stock, par value,
$.01 per share and (ii) any share capital into which such Common Stock shall have been changed or any share capital resulting from a reclassification of such Common Stock. 

(h) “Convertible Securities” means any stock or securities (other than Options) directly or indirectly convertible into or
exercisable or exchangeable for Common Stock. 
 (i) “Eligible Market” means the Principal Market, The NASDAQ Global
Market, The NASDAQ Global Select Market, The New York Stock Exchange, Inc. or the NYSE MKT LLC. 
 (j) “Expiration Date”
means the sixty sixth (66th) month anniversary of the Issuance Date or, if such date falls on a day other than a Trading Day or on which trading does not take place on the Principal Market,
or, if the Principal Market is not the principal trading market for the Common Stock, then on the principal securities exchange or securities market on which the Common Stock is then traded (a “Holiday”), the next date that is not a
Holiday. 
 (k) “Options” means any rights, warrants or options to subscribe for or purchase Common Stock or Convertible
Securities. 
 (l) “Person” means an individual, a limited liability company, a partnership, a joint venture, a
corporation, a trust, an unincorporated organization, any other entity and a government or any department or agency thereof. 
 (m)
“Principal Market” means The NASDAQ Capital Market or, if the Company’s Common Stock is not then listed on the NASDAQ Capital Market, then such exchange or quotation system on which the Common Stock then primarily trades. 

(n) “Trading Day” means any day on which the Common Stock are traded on the Principal Market, or, if the Principal Market is
not the principal trading market for the Common Stock, then on the principal securities exchange or securities market on which the Common Stock are then traded; provided that “Trading Day” shall not include any day on which the
Common Stock are scheduled to trade on such exchange or market for less than 4.5 hours or any day that the Common Stock are 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). 

(o) “Weighted Average Price” means, for any security as of any date, the dollar volume-weighted average price for such
security on the Principal Market during the period beginning at 9:30:01 a.m., New York time (or such other time as the Principal 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 Principal Market publicly announces is the official close of trading), as reported by Bloomberg 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 Principal 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 Principal Market publicly announces is the official close of trading), as reported by Bloomberg, or, if no dollar
volume-weighted average price is reported for such security by Bloomberg 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 OTC Link or
“pink sheets” by OTC Markets Group Inc. (formerly Pink OTC Markets Inc.). If the Weighted Average Price cannot be calculated for a security on a particular date on any of the foregoing bases, the Weighted Average Price of such security on
such date shall be the fair market value as mutually determined by the Company and the Holder. If the Company and the Holder are unable to agree upon the fair market value of such security, then such dispute shall be resolved pursuant to
Section 10 with the term “Weighted Average Price” being substituted for the term “Exercise Price.” All such determinations shall be appropriately adjusted for any stock dividend, stock split, stock combination,
reclassification or other similar transaction during the applicable calculation period. 
 [Signature Page Follows] 

 IN WITNESS WHEREOF, the Company has caused this Warrant to Purchase Common Stock to be
duly executed as of the Issuance Date set out above. 
  

			
	CLEAN DIESEL TECHNOLOGIES, INC.
		
	By:	 	  

	Name:	 	
	Title:	 	

 EXHIBIT A 

EXERCISE NOTICE 
 TO BE
EXECUTED BY THE REGISTERED HOLDER TO EXERCISE THIS 
 WARRANT TO PURCHASE COMMON STOCK 

CLEAN DIESEL TECHNOLOGIES, INC. 

The undersigned holder hereby exercises the right to purchase
                 shares of the Common Stock (“Warrant Shares”) of Clean Diesel Technologies, Inc., a corporation existing under the laws of Delaware
(the “Company”), evidenced by the attached Warrant to Purchase Common Stock (the “Warrant”). Capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Warrant.

 15. Form of Exercise Price. The Holder intends that payment of the Exercise Price shall be made as: 

                     a “Cash
Exercise” with respect to                 Warrant Shares; or 

                     a “Cashless
Exercise” with respect to                  Warrant Shares. 

16. Payment of Exercise Price. In the event that the holder has elected a Cash Exercise with respect to some or all of the Warrant Shares to
be issued pursuant hereto, the holder shall pay the Aggregate Exercise Price by wire transfer of immediately available funds in the sum of $         to the Company in accordance with the terms of the Warrant.

 17. Delivery of Warrant Shares. The Company shall deliver to the holder
                 Warrant Shares in accordance with the terms of the Warrant. 

Date:                  ,          

 

			
	  

	Name of Registered Holder
		
	By:EX-10.1

 Exhibit 10.1 

Clean Diesel Technologies, Inc. 
 4567 Telephone Road, Suite 100

 Ventura, California 93003 
 Gentlemen: 

The undersigned (the “Investor”) hereby confirms its agreement with Clean Diesel Technologies, Inc., a Delaware corporation (the
“Company”) as follows: 
 1. This Subscription Agreement, including the Terms and Conditions For Purchase of Securities
attached hereto as Annex I (collectively, (this “Agreement”) is made as of the date set forth below between the Company and the Investor. 

2. The Company has authorized the sale and issuance to certain investors of up to an aggregate of (i) 2,030,000 authorized and
unissued shares (the “Shares”) of its common stock, par value $0.01 per share (the “Common Stock”) and (ii) warrants (each, a “Warrant” and, collectively, the “Warrants”) to
purchase up to an aggregate of 812,000 shares of Common Stock (the “Warrant Shares”), in substantially the form attached hereto as Exhibit B. The Shares and the Warrants are being sold together as units (the
“Units”), each Unit consisting of one Share and 0.4 of one Warrant, each Warrant to purchase one share of Common Stock. Units will not be separately issued or certificated and the Investor will receive Shares and Warrants comprising
the Units which will be immediately separable and transferable upon issuance. Each Investor will receive Units at an initial public offering price of $3.40 per Unit (the “Purchase Price”). The Units, the Shares, the Warrants and the
Warrant Shares are collectively referred to herein as the “Securities”. 
 3. The offering and sale of the
Securities (the “Offering”) are being made pursuant to (1) an effective Registration Statement on Form S-3, File No. 333-181443 (the “Registration Statement”) filed by the Company with the Securities and
Exchange Commission (the “Commission”) (including the prospectus contained therein (the “Base Prospectus”), (2) if applicable, certain “free writing prospectuses” (as that term is defined in Rule 405 under
the Securities Act of 1933, as amended (the “Securities Act”)), that have been or will be filed with the Commission and delivered to the Investor on or prior to the date hereof (the “Issuer Free Writing
Prospectus”), containing certain supplemental information regarding the Securities, the terms of the Offering and the Company and (3) a Prospectus Supplement (the “Prospectus Supplement” and together with the Base
Prospectus, the “Prospectus”) containing certain supplemental information regarding the Securities and terms of the Offering that has been or will be filed with the Commission and delivered to the Investor (or made available to the
Investor by the filing by the Company of an electronic version thereof with the Commission). 
 4. The Company and the Investor agree
that at the Closing (as defined in Section 3.1 of Annex I), the Investor will purchase from the Company and the Company will issue and sell to the Investor the Units set forth below for the aggregate Purchase Price set forth below.
The Units shall be purchased pursuant to the Terms and Conditions for Purchase of Securities attached hereto as Annex I and incorporated herein by this reference as if fully set forth herein. The Investor acknowledges that the Offering
is not being underwritten by the placement agents (the “Placement Agents”) named in the Prospectus Supplement and that there is no minimum offering amount. 

5. In connection with the sale of the Securities, the Company agrees that it will not, for a period of ninety (90) days from the
date of the Prospectus, (the “Lock-Up Period”) without the prior written consent of the Investor, directly or indirectly offer, sell, assign, transfer, pledge, contract to sell, or otherwise dispose of, any shares of
Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock, other than: (i) the Company’s sale of the Securities in this Offering; (ii) the issuance of options or restricted stock units to acquire
Common Stock pursuant to the Company’s stock incentive plan or other employee benefit plans as such plans are in existence on the date hereof and described in the Prospectus; and (iii) the issuance of Common Stock pursuant to the valid
exercises or settlement of options, warrants, restricted stock units or rights outstanding on the date hereof and described in the Prospectus. The Company also agrees that during such period, the Company will not file any registration statement,
preliminary prospectus or prospectus, or any amendment or supplement thereto, under the Securities Act for any such transaction or which registers, or offers for sale, Common Stock or any securities convertible into or exercisable or exchangeable
for Common Stock, except for a registration statement on Form S-8 relating to employee benefit plans or as the Investor may otherwise consent. The Company hereby agrees that (i) if it issues an earnings release or material news, or if a
material event relating to the Company occurs, during the last 

 
seventeen (17) days of the Lock-Up Period, or (ii) if prior to the expiration of the Lock-Up Period, the Company announces that it will release earnings results during the sixteen
(16)-day period beginning on the last day of the Lock-Up Period, the restrictions imposed by this paragraph (k) or the letter shall continue to apply until the expiration of the eighteen (18)-day period beginning on the issuance of the
earnings release or the occurrence of the material news or material event. 
 6. The manner of settlement of the Shares included in
the Units purchased by the Investor shall be determined by such Investor as follows (check one): 

[            ] A. [        ] A. Delivery by crediting the
account of the Investor’s prime broker (as specified by such Investor on Exhibit A annexed hereto) with the Depository Trust Company (“DTC”) through its Deposit/Withdrawal At Custodian (“DWAC”) system, whereby
Investor’s prime broker shall initiate a DWAC transaction on the Closing Date using its DTC participant identification number, and released by American Stock Transfer & Trust Company, the Company’s transfer agent (the
“Transfer Agent”), at the Company’s direction. NO LATER THAN ONE (1) BUSINESS DAY AFTER THE EXECUTION OF THIS AGREEMENT BY THE INVESTOR AND THE COMPANY, THE INVESTOR SHALL: 

 

	 	(I)	DIRECT THE BROKER-DEALER AT WHICH THE ACCOUNT OR ACCOUNTS TO BE CREDITED WITH THE SHARES ARE MAINTAINED TO SET UP A DWAC INSTRUCTING THE TRANSFER AGENT TO CREDIT SUCH ACCOUNT OR ACCOUNTS WITH THE SHARES, AND

  

	 	(II)	REMIT BY WIRE TRANSFER THE AMOUNT OF FUNDS EQUAL TO THE AGGREGATE PURCHASE PRICE FOR THE UNITS BEING PURCHASED BY THE INVESTOR TO THE FOLLOWING ACCOUNT: 

[To be separately provided to the Investor] 

—OR— 

[            ] B. [        ] B. Delivery versus payment
(“DVP”) through DTC (i.e., on the Closing Date, the Company shall issue Shares registered in the Investor’s name and address as set forth below and released by the Transfer Agent directly to the account(s) at Roth Capital
Partners, LLC (“Roth”) or Craig-Hallum Capital Group LLC (“Craig-Hallum”) identified by the Investor; upon receipt of such Shares, Roth or Craig-Hallum, as the case may be, shall promptly electronically deliver such
Shares to the Investor, and simultaneously therewith payment shall be made by Roth or Craig-Hallum by wire transfer to the Company). NO LATER THAN ONE (1) BUSINESS DAY AFTER THE EXECUTION OF THIS AGREEMENT BY THE INVESTOR AND THE COMPANY,
THE INVESTOR SHALL: 
  

	 	(I)	NOTIFY ROTH OR CRAIG-HALLUM OF THE ACCOUNT OR ACCOUNTS AT ROTH OR CRAIG-HALLUM TO BE CREDITED WITH THE SHARES BEING PURCHASED BY SUCH INVESTOR, AND 

 

	 	(II)	CONFIRM THAT THE ACCOUNT OR ACCOUNTS AT ROTH OR CRAIG-HALLUM TO BE CREDITED WITH THE SHARES BEING PURCHASED BY THE INVESTOR HAVE A MINIMUM BALANCE EQUAL TO THE AGGREGATE PURCHASE PRICE FOR THE UNITS BEING PURCHASED
BY THE INVESTOR. 

 IT IS THE INVESTOR’S RESPONSIBILITY TO (A) MAKE THE NECESSARY WIRE TRANSFER OR CONFIRM THE PROPER
ACCOUNT BALANCE IN A TIMELY MANNER AND (B) ARRANGE FOR SETTLEMENT BY WAY OF DWAC OR DVP IN A TIMELY MANNER. IF THE INVESTOR DOES NOT DELIVER THE AGGREGATE PURCHASE PRICE FOR THE UNITS OR DOES NOT MAKE PROPER ARRANGEMENTS FOR SETTLEMENT IN A
TIMELY MANNER, THE SHARES AND THE WARRANTS COMPRISING THE UNITS MAY NOT BE DELIVERED AT CLOSING TO THE INVESTOR OR THE INVESTOR MAY BE EXCLUDED FROM THE CLOSING ALTOGETHER. 

7. The executed Warrants included in the Units purchased by the Investor shall be delivered to the Investor by mail, registered in such
names and sent to such address as specified by the Investor below. 

  
 2 

 8. The Investor represents that, except as set forth below, (a) it has had no
position, office or other material relationship within the past three years with the Company or persons known to it to be affiliates of the Company, (b) it is not a member of the Financial Industry Regulatory Authority, Inc.
(“FINRA”) or an Associated Person (as such term is defined under the FINRA’s NASD Membership and Registration Rules Section 1011) as of the Closing, and (c) neither the Investor nor any group of Investors (as
identified in a public filing made with the Commission) of which the Investor is a part in connection with the Offering, acquired, or obtained the right to acquire, 20% or more of the Common Stock (or securities convertible into or exercisable for
Common Stock) or the voting power of the Company on a post-transaction basis. Exceptions: 
  

					
		 	  
	 	

 (If no exceptions, write “none.” If left blank, response will be deemed to be “none.”)

 9. The Investor represents that it has received (or otherwise had made available to it by the filing by the Company of an
electronic version thereof with the Commission) the Base Prospectus, dated May 21, 2012, which is a part of the Company’s Registration Statement, the documents incorporated by reference therein and any free writing prospectus
(collectively, the “Disclosure Package”), prior to or in connection with the receipt of this Agreement. The Investor acknowledges that, prior to the delivery of this Agreement to the Company, the Investor will receive certain
additional information regarding the Offering, including pricing information (the “Offering Information”). Such information may be provided to the Investor by any means permitted under the Securities Act, including the Prospectus
Supplement, a free writing prospectus and oral communications. 
 10. No offer by the Investor to buy Shares and Warrants will be
accepted and no part of the Purchase Price will be delivered to the Company until the Investor has received the Offering Information and the Company has accepted such offer by countersigning a copy of this Agreement, and any such offer may be
withdrawn or revoked, without obligation or commitment of any kind, at any time prior to the Company (or Roth or Craig-Hallum on behalf of the Company) sending (orally, in writing or by electronic mail) notice of its acceptance of such offer. An
indication of interest will involve no obligation or commitment of any kind until the Investor has been delivered the Offering Information and this Agreement is accepted and countersigned by or on behalf of the Company. 

11. The Company acknowledges that the only material, non-public information relating to the Company or its subsidiaries that the
Company, its employees or agents has provided to the Investor in connection with the Offering prior to the date hereof is the existence of the Offering. 

  
 3 

 Number of Shares:
                                         

Purchase Price per Unit:
$                                         

Aggregate Purchase Price:
$                                         

Number of Warrant Shares subject to Warrants (Equal to Number of Shares multiplied by 0.40 and rounded down to the nearest whole number):
                                         

Please confirm that the foregoing correctly sets forth the agreement between us by signing in the space provided below for that purpose. 

 

			
	Dated as of:             , 2014
	
	  

	INVESTOR
		
	By:	 	  

		
	Print Name:	 	  

		
	Title:	 	  

		
	Address:	 	  

	  

 Agreed and Accepted 
 this
1st day of April, 2014: 
  

			
	CLEAN DIESEL TECHNOLOGIES, INC.
		
	By:	 	  

		 	Title

  
 4 

 ANNEX I 

TERMS AND CONDITIONS FOR PURCHASE OF SECURITIES 

1. Authorization and Sale of the Securities. Subject to the terms and conditions of this Agreement, the Company has authorized the sale
of the Securities. 
 2. Agreement to Sell and Purchase the Securities; Placement Agents. 

2.1 At the Closing (as defined in Section 3.1), the Company will sell to the Investor, and the Investor will purchase from
the Company, upon the terms and conditions set forth herein, the number of Units set forth on the last page of the Agreement to which these Terms and Conditions for Purchase of Securities are attached as Annex I (the “Signature
Page”) for the aggregate purchase price therefor set forth on the Signature Page. 
 2.2 The Company proposes to enter into
substantially this same form of Subscription Agreement with certain other investors (the “Other Investors”) and expects to complete sales of Units to them. The Investor and the Other Investors are hereinafter sometimes collectively
referred to as the “Investors,” and this Agreement and the Subscription Agreements executed by the Other Investors are hereinafter sometimes collectively referred to as the “Agreements.” 

2.3 Investor acknowledges that the Company has agreed to pay Roth Capital Partners, LLC and Craig-Hallum Capital Group LLC
(collectively, the “Placement Agents”) a fee (the “Placement Fee”) and to reimburse the Placement Agents for certain expenses in respect of the sale of the Units to the Investor. 

2.4 The Company has entered into a Placement Agent Agreement, dated the date hereof, (the “Placement Agreement”), with
the Placement Agents that contains certain representations, warranties, covenants and agreements of the Company that may be relied upon by the Investor, which shall be a third party beneficiary thereof. The Company confirms that neither it nor any
other Person acting on its behalf has provided the Investor or their agents or counsel with any information that constitutes or could reasonably be expected to constitute material, nonpublic information, except as will be disclosed in the Prospectus
and/or in the Company’s Form 8-K to be filed with the Commission in connection with the Offering. The Company understands and confirms that the Investor will rely on the foregoing representations in effecting transactions in securities of the
Company. 
 3. Closings and Delivery of the Securities and Funds. 

3.1 Closing. The completion of the purchase and sale of the Units (the “Closing”) shall occur at a place and
time (the “Closing Date”) to be specified by the Company and the Placement Agents, and of which the Investors will be notified in advance by the Placement Agents, in accordance with Rule 15c6-l promulgated under the Securities
Exchange Act of 1934, as amended (the “Exchange Act”). At the Closing, (a) the Company shall cause American Stock Transfer & Trust Company, the Company’s “Transfer Agent”, to deliver to the Investor the
number of Shares included in the Units purchased by the Investor as set forth on the Signature Page registered in the name of the Investor or, if so indicated on the Investor Questionnaire attached hereto as Exhibit A, in the name of a
nominee designated by the Investor, (b) the Company shall cause to be delivered to the Investor a warrant certificate for the number of Warrants included in the Units purchased by the Investor as set forth on the Signature Page and (c) the
aggregate purchase price for the Units being purchased by the Investor will be delivered by or on behalf of the Investor to the Company. 

3.2 Conditions to the Obligations of the Parties. 

(a) Conditions to the Company’s Obligations. The Company’s obligation to issue and sell the Units to
the Investor shall be subject to: (i) the receipt by the Company of the purchase price for the Units being purchased hereunder as set forth on the Signature Page and (ii) the accuracy of the representations and warranties made by the
Investor and the fulfillment of those undertakings of the Investor to be fulfilled prior to the Closing Date. 
 (b)
Conditions to the Investor’s Obligations. The Investor’s obligation to purchase the Units will be subject to the accuracy of the representations and warranties made by the Company and the fulfillment of those undertakings of
the Company to be fulfilled prior to the Closing 

  
 5 

 
Date, including without limitation, those contained in the Placement Agreement, and to the condition that the Placement Agents shall not have: (a) terminated the Placement Agreement pursuant
to the terms thereof or (b) determined that the conditions to the closing in the Placement Agreement have not been satisfied. The Investor’s obligations are expressly not conditioned on the purchase by any or all of the Other Investors of
the Units that they have agreed to purchase from the Company. The Investor understands and agrees that, in the event that the Placement Agents in their sole discretion determine that the conditions to closing in the Placement Agreement have not been
satisfied or if the Placement Agreement may be terminated for any other reason permitted by such Placement Agreement, then the Placement Agents may, but shall not be obligated to, terminate such Agreement, which shall have the effect of terminating
this Subscription Agreement pursuant to Section 14 below. 
 3.3 Delivery of Funds. 

(a) DWAC Delivery. If the Investor elects to settle the Shares included in the Units purchased by such Investor through
DTC’s Deposit/Withdrawal at Custodian (“DWAC”) delivery system, no later than one (1) business day after the execution of this Agreement by the Investor and the Company, the Investor shall remit by wire
transfer the amount of funds equal to the aggregate purchase price for the Units being purchased by the Investor to the following account designated by the Company: 

[To be separately provided to the Investor] 

(b) Delivery Versus Payment through The Depository Trust Company. If the Investor elects to settle the Shares included
in the Units purchased by such Investor by delivery versus payment through DTC, no later than one (1) business day after the execution of this Agreement by the Investor and the Company, the Investor shall confirm that the account
or accounts at either of the Placement Agents to be credited with the Shares being purchased by the Investor have a minimum balance equal to the aggregate purchase price for the Units being purchased by the Investor. 

3.4 Delivery of Shares. 

(a) DWAC Delivery. If the Investor elects to settle the Shares included in the Units purchased by such Investor through
DTC’s DWAC delivery system, no later than one (1) business day after the execution of this Agreement by the Investor and the Company, the Investor shall direct the broker-dealer at which the account or accounts to be credited
with the Shares being purchased by such Investor are maintained, which broker/dealer shall be a DTC participant, to set up a DWAC instructing the Transfer Agent to credit such account or accounts with the Shares. Such DWAC instruction shall indicate
the settlement date for the deposit of the Shares, which date shall be provided to the Investor by the Placement Agents. Upon the closing of the Offering, the Company shall direct the Transfer Agent to credit the Investor’s account or accounts
with the Shares pursuant to the information contained in the DWAC. 
 (b) Delivery Versus Payment through The Depository
Trust Company. If the Investor elects to settle the Shares included in the Units purchased by such Investor by delivery versus payment through DTC, no later than one (1) business day after the execution of this Agreement by the
Investor and the Company, the Investor shall notify either of the Placement Agents of the account or accounts at such Placement Agent to be credited with the Shares being purchased by such Investor. On the Closing Date, the Company shall
deliver the Shares to the Investor through DTC directly to the account(s) at such Placement Agent identified by Investor. Upon receipt of such Shares, such Placement Agent shall promptly electronically deliver such Shares to the Investor, and
simultaneously therewith payment shall be made by such Placement Agent by wire transfer to the Company. 
 4. Representations, Warranties
and Covenants of the Investor. 
 The Investor acknowledges, represents and warrants to, and agrees with, the Company and the Placement
Agents that: 
 4.1 The Investor (a) is knowledgeable, sophisticated and experienced in making, and is qualified to make
decisions with respect to, investments in securities presenting an investment decision like that involved in the purchase of the Securities, including investments in securities issued by the Company and

  
 6 

 
investments in comparable companies, (b) has answered all questions on the Signature Page and the Investor Questionnaire and the answers thereto are true and correct as of the date hereof
and will be true and correct as of the Closing Date and (c) in connection with its decision to purchase the Shares and the Warrants set forth on the Signature Page, has received and is relying only upon the Disclosure Package and the documents
incorporated by reference therein and the Offering Information. 
 4.2 (a) No action has been or will be taken in any jurisdiction
outside the United States by the Company or the Placement Agents that would permit an offering of the Securities, or possession or distribution of offering materials in connection with the issue of the Securities in any jurisdiction outside the
United States where action for that purpose is required, (b) if the Investor is outside the United States, it will comply with all applicable laws and regulations in each foreign jurisdiction in which it purchases, offers, sells or delivers
Securities or has in its possession or distributes any offering material, in all cases at its own expense and (c) neither of the Placement Agents is authorized to make and has not made any representation, disclosure or use of any information in
connection with the issue, placement, purchase and sale of the Securities, except as set forth or incorporated by reference in the Base Prospectus, the Prospectus Supplement or any free writing prospectus. 

4.3 (a) The Investor has full right, power, authority and capacity to enter into this Agreement and to consummate the transactions
contemplated hereby and has taken all necessary action to authorize the execution, delivery and performance of this Agreement, and (b) this Agreement constitutes a valid and binding obligation of the Investor enforceable against the Investor in
accordance with its terms, except as enforceability may be limited by applicable bankruptcy, insolvency, reorganization, moratorium or similar laws affecting creditors’ and contracting parties’ rights generally and except as enforceability
may be subject to general principles of equity (regardless of whether such enforceability is considered in a proceeding in equity or at law) and except as to the enforceability of any rights to indemnification or contribution that may be violative
of the public policy underlying any law, rule or regulation (including any federal or state securities law, rule or regulation). 
 4.4
The Investor understands that nothing in this Agreement, the Prospectus, the Disclosure Package, the Offering Information or any other materials presented to the Investor in connection with the purchase and sale of the Units constitutes legal,
tax or investment advice. The Investor has consulted such legal, tax and investment advisors and made such investigation as it, in its sole discretion, has deemed necessary or appropriate in connection with its purchase of Units. The Investor also
understands that there is no established public trading market for the Warrants being offered in the Offering, and that the Company does not expect such a market to develop. In addition, the Company does not intend to apply for listing of the
Warrants on any securities exchange or other trading market. The Investor understands that without an active market, the liquidity of the Warrants will be limited. 

4.5 The Investor will maintain the confidentiality of all information acquired as a result of the transactions contemplated hereby
prior to the public disclosure of that information by the Company in accordance with Section 13 of this Annex. 
 4.6 Since the
time at which either of the Placement Agents first contacted such Investor about the Offering, the Investor has not disclosed any information regarding the Offering to any third parties (other than its legal, accounting and other advisors) and has
not engaged in any purchases or sales of the securities of the Company (including, without limitation, any Short Sales (as defined herein) involving the Company’s securities). The Investor covenants that it will not engage in any purchases or
sales of the securities of the Company (including Short Sales) prior to the time that the transactions contemplated by this Agreement are publicly disclosed. The Investor agrees that it will not use any of the Securities acquired pursuant to this
Agreement to cover any short position in the Common Stock if doing so would be in violation of applicable securities laws. For purposes hereof, “Short Sales” include, without limitation, all “short sales” as defined in Rule 200
promulgated under Regulation SHO under the Exchange Act, whether or not against the box, and all types of direct and indirect stock pledges, forward sales contracts, options, puts, calls, short sales, swaps, “put equivalent positions” (as
defined in Rule 16a-1(h) under the Exchange Act) and similar arrangements (including on a total return basis), and sales and other transactions through non-U.S. broker dealers or foreign regulated brokers. 

5. Survival of Representations, Warranties and Agreements; Third Party Beneficiary. Notwithstanding any investigation made by any party
to this Agreement or by either of the Placement Agents, all covenants, agreements, representations and warranties made by the Company and the Investor herein will survive the execution of this Agreement, the delivery to the Investor of the Shares
and Warrants comprising the Units being purchased and the payment therefor. The Placement Agents shall be third party beneficiaries with respect to the representations, warranties and agreements of the Investor in Section 4 hereof. 

  
 7 

 6. Notices. All notices, requests, consents and other communications hereunder will be in
writing, will be mailed (a) if within the domestic United States by first-class registered or certified airmail, or nationally recognized overnight express courier, postage prepaid, or by facsimile or (b) if delivered from outside the
United States, by International Federal Express or facsimile, and will be deemed given (i) if delivered by first-class registered or certified mail domestic, three business days after so mailed, (ii) if delivered by nationally recognized
overnight carrier, one business day after so mailed, (iii) if delivered by International Federal Express, two business days after so mailed and (iv) if delivered by facsimile, upon electronic confirmation of receipt and will be delivered
and addressed as follows: 
 (a) if to the Company, to: 

Clean Diesel Technologies, Inc. 

4567 Telephone Road, Suite 100 

Ventura, California 93003 

Attention: Nikhil Mehta, Chief Financial Officer 

Fax: (805) 639-9466 

with a copy (which shall not constitute notice) to: 

DLA Piper LLP (US) 
 2525 East
Camelback Road, Suite 1000 
 Phoenix, Arizona 85016 

Attention: Steven Pidgeon, Esq. 

Fax: (480) 646-5524 

(b) if to the Investor, at its address on the Signature Page hereto, or at such other address or addresses as may have been
furnished to the Company in writing. 
 7. Changes. This Agreement may not be modified or amended except pursuant to an instrument in
writing signed by the Company and the Investor. 
 8. Headings. The headings of the various sections of this Agreement have been
inserted for convenience of reference only and will not be deemed to be part of this Agreement. 
 9. Severability. In case any
provision contained in this Agreement should be invalid, illegal or unenforceable in any respect, the validity, legality and enforceability of the remaining provisions contained herein will not in any way be affected or impaired thereby. 

10. Governing Law. This Agreement will be governed by, and construed in accordance with, the internal laws of the State of New York,
without giving effect to the principles of conflicts of law that would require the application of the laws of any other jurisdiction. 

11. Counterparts. This Agreement may be executed in two or more counterparts, each of which will constitute an original, but all of
which, when taken together, will constitute but one instrument, and will become effective when one or more counterparts have been signed by each party hereto and delivered to the other parties. The Company and the Investor acknowledge and agree that
the Company shall deliver its counterpart to the Investor along with the Prospectus Supplement (or the filing by the Company of an electronic version thereof with the Commission). 

12. Confirmation of Sale. The Investor acknowledges and agrees that such Investor’s receipt of the Company’s signed
counterpart to this Agreement, together with the Prospectus Supplement (or the filing by the Company of an electronic version thereof with the Commission), shall constitute written confirmation of the Company’s sale of the Units to such
Investor. 

  
 8 

 13. Press Release; 8-K Filing. The Company and the Investor agree that the Company shall
prior to the opening of the financial markets in New York City on April 1, 2014 (a) issue a press release announcing the Offering and disclosing all material information regarding the Offering and (b) file a current report on Form 8-K
with the Securities and Exchange Commission including, but not limited to, a form of this Agreement and the form of Warrant as exhibits thereto (the “8-K”). Effective upon the filing of the 8-K, the Company acknowledges and agrees
that any and all confidentiality and similar obligations under any agreement, whether written or oral, between the Company, any of its subsidiaries or any of their respective officers, directors, affiliates, employees or agents, on the one hand, and
the Investor or any of its affiliates, on the other hand, shall terminate. From and after the filing of the 8-K with the SEC, the Investor shall not be deemed to be in possession of any material, nonpublic information received from the Company, any
of its subsidiaries or any of their respective officers, directors, employees or agents. 
 14. Termination. In the event that the
Placement Agreement is terminated by the Placement Agents pursuant to the terms thereof, this Agreement shall terminate without any further action on the part of the parties hereto. 

  
 9 

 EXHIBIT A 

CLEAN DIESEL TECHNOLOGIES, INC. 

INVESTOR QUESTIONNAIRE 
 Pursuant to
Section 3 of Annex I to the Agreement, please provide us with the following information: 
  

					
	1.	 	 The exact name that your Shares and Warrants are to be registered in. You may use a nominee name if appropriate:
	 	  

	2.	 	 The relationship between the Investor and the registered holder listed in response to item 1 above:
	 	  

	3.	 	 The mailing address of the registered holder listed in response to item 1 above:
	 	  

	4.	 	 The Social Security Number or Tax Identification Number of the registered holder listed in the response to item 1 above:
	 	  

	5.	 	 Name of DTC Participant (broker-dealer at which the account or accounts to be credited with the Shares are maintained):
	 	  

	6.	 	 DTC Participant Number:
	 	  

	7.	 	 Name of Account at DTC Participant being credited with the Shares:
	 	  

	8.	 	 Account Number at DTC Participant being credited with the Shares:
	 	  

  
 A-1 

 EXHIBIT B 

FORM OF WARRANT 

  
 B-1

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