Exhibit 4.1

The shares represented by this certificate are transferable at the offices of American Stock Transfer & Trust Company, LLC, in New York and Capita IRG Plc in the United Kingdom. COMMON STOCK CLEAN DIESEL TECHNOLOGIES, INC. INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE SEE REVERSE FOR CERTAIN DEFINITIONS CUSIP 18449c 40 1 CERTIFIES THAT: is the owner of FULLY PAID AND NONASSESSABLE SHARES OF THE COMMON STOCK, $.01 PAR VALUE, OF transferable on the books of the Corporation in person or by attorney upon surrender of this certificate properly endorsed or assigned. This certificate and the shares represented hereby arc subject to the laws of the State of Delaware, and to the Certificate of Incorporation and Bylaws of the Corporation, as now or hereafter amended. This certificate is not valid until countersigned by the Transfer Agent and registered by the Registrar. WITNESS the facsimile sea the Corporation and the facsimile signatures of its duly authorized officers.

THE CORPORATION WILL FURNISH TO ANY STOCKHOLDER, UPON REQUEST AND WITHOUT CHARGE, A FULL STATEMENT OF THE DESIGNATIONS, RELATIVE RIGHTS, PREFERENCES AND LIMITATIONS OF THE SHARES OF EACH CLASS AND SERIES AUTHORIZED TO BE ISSUED, SO FAR AS THE SAME HAVE BEEN DETERMINED, AND OF THE AUTHORITY, IF ANY, OF THE BOARD TO DIVIDE THE SHARES INTO CLASSES OR SERIES AND TO DETERMINE AND CHANGE THE RELATIVE RIGHTS, PREFERENCES AND LIMITATIONS OF ANY CLASS OR SERIES. SUCH REQUEST MAY BE MADE TO THE SECRETARY OF THE CORPORATION OR TO THE TRANSFER AGENT NAMED ON THIS CERTIFICATE.

     The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations:

TEN COM	-	as tenants in common	UNIF GIFT (TRANS) MIN ACT                                      Custodian
TEN ENT	-	as tenants by the entireties			(Cust)
JT TEN	-	as joint tenants with right of survivorship and not as tenants in common	under Uniform Gifts (Transfer) to lviinors
			Act                     ,
				(State)

Additional abbreviations may also be used though not in the above list.

FOR VALUE RECEIVED,                                                            hereby sells, assigns and transfers unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
     IDENTIFYING NUMBER OF ASSIGNEE

PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS OF ASSIGNEE

Shares

of the stock represented by the within Certificate, and do hereby irrevocably constitute and appoint

Attorney

to transfer the said Stock on the books of the within-named Corporation with full power of substitution in the premises.

Dated                                         

NOTICE: THE SIGNATURES TO THIS ASSIGNMENT MUST CORRESPOND WITH THE NAME(S) AS WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR WITHOUT (ILLEGIBLE FOR THE REST)

Signature(s) Guaranteed

By

THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM) PURSUANT TO S.E.C. RULE 17Ad- 15.