Document:

EX-4.1

 Exhibit 4.1 

FORM OF SERIES A WARRANT 

CLEAN DIESEL TECHNOLOGIES, INC. 

Warrant To Purchase Common Stock 
 Warrant
No.: 
 Number of Shares of Common Stock:
                     
 Date of Issuance: November
    , 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 Series A 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 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 13. 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 November     , 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 $3.25, 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.
	 B=
	 	the arithmetic average of the Closing Sale Prices of the Common Stock for the five (5) 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, 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 9.99% (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 5(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. 
 (e)
NOTICES. Whenever notice is required to be given under this Warrant, unless otherwise provided herein, such notice shall be given in writing, (a) if delivered from 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 (c) 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: 

	 	(i)	if to the Company, to: 

 Clean Diesel Technologies Inc. 

1621 Fiske Place 
 Oxnard,
California 93033 
 Attention: Chief Financial Officer 

Facsimile: (805) 639-9466 

With Copies to: 
 DLA LLP (US)

 2525 E. Camelback Rd, Suite 1000 

Phoenix, AZ 85016 
 Attention:
Steven Pidgeon 
 Facsimile: (480) 646-5524 

(ii) if to the Holder, at the address of the Holder appearing on the signature page to the Subscription Agreement or such other address
delivered by the Holder subsequently to the Company. 
 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. 
 6. 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. 
 7. 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. 
 8. 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. 

9. 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. 

10. 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. 
 11. TRANSFER. This Warrant
may be offered for sale, sold, transferred or assigned without the consent of the Company. 
 12. 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). 

13. 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 five year 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) “Subscription Agreement” means the Subscription Agreement dated November     , 2014 by and between
the Company and the Holder. 
 (o) “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). 

(p) “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 Series A 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. 
 14. 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. 

15. 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. 
 16. 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-4.2

 Exhibit 4.2 

FORM OF SERIES B WARRANT 

CLEAN DIESEL TECHNOLOGIES, INC. 

Warrant To Purchase Common Stock 

Warrant No.: 
 Number of Shares of Common Stock:

 Date of Issuance: November     , 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 Series B 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 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 13. 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 November     , 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) 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 a 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”), 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 $0.01, 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. The Holder may exercise this
Warrant in whole or in part by electing 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.
	B=	 	the arithmetic average of the Closing Sale Prices of the Common Stock for the five (5) 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, 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 9.99% (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 5(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. 

(e) NOTICES. The Company shall provide Holder with prompt written notice of all actions taken pursuant to this Warrant.
Whenever notice is required to be given under this Warrant, unless otherwise provided herein, such notice shall be given in writing, (a) if delivered from 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 (c) 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: 
  

	 	(i)	if to the Company, to: 

 Clean Diesel Technologies Inc. 

1621 Fiske Place 
 Oxnard,
California 93033 
 Attention: Chief Financial Officer 

Facsimile: 
 With Copies to: 

DLA LLP (US) 
 2525 E. Camelback
Rd, Suite 1000 
 Phoenix, AZ 85016 

Attention: Steven Pidgeon 

Facsimile: 

 (ii) if to the Holder, at the address of the Holder appearing on signature pages to the
Subscription Agreement or such other address delivered by the Holder subsequently to the Company. 
 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. 
 6.
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. 
 7. 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. 

8. 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. 

9. 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. 

10. 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. 
 11. TRANSFER. This Warrant may be offered for sale, sold, transferred or assigned without the consent of the Company.

 12. 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). 
 13. 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 six 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) “Subscription Agreement” means the Subscription Agreement dated November     , 2014 by and between
the Company and the Holder. 

 (o) “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). 

(p) “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 Series B 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. 
 Exercise Price. The Holder intends that payment of the Exercise Price shall be made as: 

a “Cashless Exercise” with respect to
                     Warrant Shares. 

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:

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