Exhibit 10.4
 Please execute signature page and fax the
Commitment Letter to [NAME] at Clean Diesel
Technologies, Inc. [NUMBER]
 Clean Diesel Technologies, Inc.
Offshore Private Placement of Up to USD $ [ Insert Number ] of Units
Form of Commitment Letter
 This letter is directed at persons having professional experience in matters relating to
investments and any investment in the Company hereunder will be engaged in only with such persons.
Persons who do not have professional experience in matters relating to investments should not sign
this letter.
 Insert Name Buyer Insert Address Company Offering Insert number Act Merger CSI
 Units:
    
    Each Unit shall consist of (a) that number of shares (each, a Primary Share) of the Companys common
stock, par value $0.01 per share (the Company Common Stock), as is equal to the quotient obtained by
taking the product obtained by multiplying U.S. $ [Insert number] by the number of Units being subscribed
to, and dividing said product by the average of the consolidated closing bid price of one share of Company
Common Stock as reported on the NASDAQ Stock Market, LLC (Closing Bid Price), for the twenty (20)
trading days immediately preceding the date on which the Merger is publicly announced, and (b) one (1)
Warrant (the Warrant) to purchase one (1) share of Company Common Stock (each, a Warrant Share). The
form of Warrant being issued is set forth as Schedule A hereto, and the terms and conditions of said
Warrants, which terms and conditions are described below under the heading Warrants, are as set forth
therein.Unit Price:
    
    The purchase price per Unit (the
Purchase Price) shall be $ [Insert number].Commitment:
    
    Buyer agrees to purchase from Company [Insert number]Units and to pay a total Purchase Price for such
Units equal to U.S. $ [Insert number] multiplied by the number of Units being acquired by such Buyer, and,
subject to the terms and conditions set forth herein, Company agrees to sell and issue to Buyer at the
Closing the Primary Shares and Warrants comprising the Units. Buyer acknowledges that this commitment (i)
is irrevocable, (ii) is conditioned upon acceptance by or on behalf of the Company and may be accepted or
rejected in whole or in part by the Company in its sole discretion and (iii) will expire if not accepted
by the Company on or prior to six months from the date hereof.




---



##### 



Warrants:
    
    The Warrants shall be immediately exercisable upon issue, have an exercise price per Warrant Share equal
to the quotient obtained by dividing (i) U.S. $30 million by (ii) the number of outstanding shares of
Company Common Stock immediately upon the occurrence of the Merger (and giving effect thereto). The
Warrants will have an expiration date upon the earlier to occur of (x) the third anniversary of the
consummation of the Merger or (y) the forty-fifth day after the Company provides notice to the holder of
the Warrant that the Closing Bid Price had exceeded 130% of the exercise price for ten consecutive trading
days. The Warrants would not be publicly traded or registered on any securities exchange. The form and
the terms and conditions of the Warrants shall be that of
Schedule A attached to this Commitment Letter
and the terms and conditions set forth on said Schedule A, and not the summary set forth in this
paragraph, shall govern the interpretation of the Warrants.Reverse Stock Split:
    
    In connection with the Merger, the Company will effect a reverse stock split. The numbers of Primary
Shares and Warrant Shares in this Commitment Letter, as well as the Purchase Price per Unit and the
Closing Bid Price set forth herein are pre-split, and will be adjusted to give effect to the reserve stock
split.Buyer Status:
    
    Buyer represents that it is a Qualified Investor within the meaning of Section 86 of the Financial
Services and Markets Act 2000 and an investment professional within the meaning of Article 19 of the
FSMA 2000 (Financial Promotion) Order 2005 and is not a U.S. Person within the meaning of Rule 902 of
Regulation S promulgated under the Act.Voting Rights:
    
    Primary Shares and Warrant Shares shall have one vote per share in accordance with Delaware law. Warrant
Shares shall have no voting rights until the Warrants are exercised and the Warrant Shares are issued and
outstanding. Warrants shall have no voting rights.Purpose:
    
    Company shall apply the total Purchase Price of the Units sold in the Offering toward the general
corporate expenses of the Company.Resale 
Limitations:
    
    Buyer agrees to not sell any Primary Shares or the Warrants or any Warrant Shares for a period of not less
than six (6) months from the date of issuance by the Company of the relevant Primary Shares, Warrant or
Warrant Shares to Buyer. Moreover, the purchase and sale of the Primary Shares, Warrants and Warrant
Shares are subject to Regulation S promulgated under the Act by the U.S. Securities and Exchange
Commission and relating to an available exemption from registration for the sale of securities by U.S.
companies in offshore transactions. To that end Buyer represents, certifies and agrees that (i) it is not
a U.S Person (within the meaning of Regulation S) and is not acquiring the Primary Shares, Warrants and
Warrant Shares for the account or benefit of any U.S. Person, (ii) Buyer did not become aware of the
Company or the Units through any form of directed selling efforts (as defined in Rule 902 of Regulation
S), and no general solicitation or general advertising in violation of the Act has been or will be used
nor will any offers by means of any directed selling efforts in the United States be made by Buyer or any
of its representatives in connection with the offer and sale of any of the Units or the Warrant Shares,
(iii) at the time of the origination of contact concerning the transactions contemplated by this
Commitment Letter and on the date of execution and
 2




---



##### 



delivery of this Commitment Letter by Buyer, Buyer was outside the United
States, (iv) with respect to the Primary Shares, Warrants and Warrant
Shares, it shall comply with the Transfer Restrictions set out on
Schedule B attached to this Commitment Letter and made a part
hereof, (v) that such Transfer Restrictions shall be set out in a legend on
certificate(s) representing the Primary Shares, the Warrant Shares and the
Warrants, and (vi) that the Company will refuse (or cause its transfer agent
and registrar to refuse) transfer and registration of any Primary Shares or
Warrant Shares or Warrant transferred other than in accordance with the
Transfer Restrictions.Payment:
    
    Payment shall be made by Buyer into escrow with the Company
on such date as the Company notifies the Buyer of at least
two (2) days prior thereto (the Payment Date) by wire
transfer to the Companys account, in U.S. Dollars, to
[Insert Bank Account Info]. The Payment Date, to be
selected by the Company, shall be not less than five (5)
days, and not more than ten (10) days, from the anticipated
Closing Date (as defined below). Notwithstanding the
earlier Payment Date, the closing with respect to the
Primary Shares and the Warrants (the Closing) shall occur
substantially simultaneously with the consummation of the
Merger and the date of such consummation shall be referred
to as the Closing Date. Subsequent to the Closing, the
Company shall deliver certificates evidencing the Primary
Shares registered with the Companys transfer agent and the
Warrants registered on the books of the Company, in each
case, in the name and address of the Buyer as set out above
in the ordinary course of business; provided, however, that
the Buyer shall be the owner of such Primary Shares and
Warrants from the Closing Date. If, subsequent to the
Payment Date, the Company determines that the Closing will
not occur, the Company shall promptly return the funds so
deposited in escrow to the Buyer without interest.Law:
    
    This Commitment Letter and the purchase of the Primary
Shares, the Warrants and the Warrant Shares shall be
governed by Delaware law without reference to the conflicts
of laws rules of any jurisdiction.Miscellaneous:
    
    This Commitment Letter is not assignable by Buyer without
the consent of the Company. The representations and
warranties made by the Buyer in this Commitment Letter
shall survive the Closings. Schedule B is an integral part
of this Commitment Letter and shall be deemed incorporated
by reference herein. This Commitment Letter may be
executed in one or more counterparts, all of which together
shall constitute one instrument.Signatures:
    
    This Commitment Letter to buy and sell Units has been
executed and delivered by the following authorized
representatives of the Buyer and the Company.
 [Signature page follows.]
 
 3




---



##### 



Clean Diesel Technologies, Inc.
    
    [Insert Name of Buyer]By:
    
    By:Name:
    
    Name:Title:
    
    Title:No. of Units:Total Purchase Price:
 
 4




---



##### 



[Form of Reg S Warrant]
 
 No.
 THIS WARRANT HAS NOT BEEN AND WILL NOT REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR APPLICABLE STATE SECURITIES LAWS. THE HOLDER HEREOF, BY PURCHASING THIS
WARRANT, AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS WARRANT MAY NOT BE OFFERED, SOLD,
PLEDGED, OR OTHERWISE TRANSFERRED BY SUCH HOLDER PRIOR TO THE LATER OF THE (X) SIX MONTHS
FOLLOWING THE ISSUANCE HEREOF OR (Y) IF APPLICABLE, THREE MONTHS AFTER IT CEASES TO BE AN
AFFILIATE, OTHER THAN (1) TO THE COMPANY, (2) PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT UNDER THE U.S. SECURITIES ACT OF 1933, AS AMENDED (THE SECURITIES ACT), AND IN
ACCORDANCE WITH ANY APPLICABLE LAWS OF ANY STATE OF THE UNITED STATES, (3) IN AN OFFSHORE
TRANSACTION COMPLYING WITH REGULATION S UNDER THE SECURITIES ACT, (4) PURSUANT TO AN
EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT PROVIDED BY RULE 144, IF APPLICABLE,
UNDER THE SECURITIES ACT OR (5) IN A TRANSACTION THAT DOES NOT REQUIRE REGISTRATION UNDER
THE SECURITIES ACT BUT IS IN ACCORDANCE WITH APPLICABLE STATE SECURITIES LAWS AND IN
RELATION TO WHICH THE HOLDER HAS FURNISHED TO THE COMPANY AN OPINION TO SUCH EFFECT FROM
COUNSEL OF RECOGNISED STANDING IN FORM AND SUBSTANCE SATISFACTORY TO THE COMPANY PRIOR TO
SUCH OFFER, SALE, PLEDGE OR TRANSFER. THE HOLDER HEREOF, BY PURCHASING THIS WARRANT,
REPRESENTS AND AGREES FOR THE BENEFIT OF THE COMPANY THAT IT IS A NON-U.S. PERSON, AND
ACKNOWLEDGES THAT HEDGING TRANSACTIONS INVOLVING THIS WARRANT MAY NOT BE CONDUCTED UNLESS
CONDUCTED IN COMPLIANCE WITH THE SECURITIES ACT.
 [Insert Date
 Insert no. of Shares] Shares
 Warrant for Purchase of Common Stock
of Clean Diesel Technologies, Inc.
(a Delaware Corporation)
 [Insert Name] Insert Address [Insert No. of Shares] X.XX 1
 
 1
    
    Price to be determined by the Company by
determining the quotient of $30,000,000 divided by the number of outstanding
Shares immediately upon the occurrence of the merger (the Merger) of a
subsidiary of the Company with and into Catalytic Solutions, Inc., a California
corporation, and giving effect thereto. A-1




---



##### 



Commitment Letter
 Exercise; Expiration Date
 [insert
date] 2
  No Stockholder Rights
 Compliance with Securities Laws
 
 2
    
    Insert third anniversary of the date of the
Merger. A-2




---



##### 



THIS SECURITY HAS NOT BEEN AND WILL NOT REREGISTERED UNDER THE SECURITIES ACT OF
1933, AS AMENDED, OR APPLICABLE STATE SECURITIES LAWS. THE HOLDER HEREOF, BY
PURCHASING THIS SECURITY, AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS SECURITY
MAY NOT BE OFFERED, SOLD, PLEDGED, OR OTHERWISE TRANSFERRED BY SUCH HOLDER PRIOR TO
THE LATER OF (X) SIX MONTHS FOLLOWING THE ISSUANCE HEREOF OR (Y) IF APPLICABLE,
THREE MONTHS AFTER IT CEASES TO BE AN AFFILIATE, OTHER THAN (1) TO THE COMPANY, (2)
PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT AND IN
ACCORDANCE WITH ANY APPLICABLE LAWS OF ANY STATE OF THE UNITED STATES, (3) IN AN
OFFSHORE TRANSACTION COMPLYING WITH REGULATION S UNDER THE SECURITIES ACT, (4)
PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT PROVIDED BY RULE
144, IF APPLICABLE, UNDER THE SECURITIES ACT OR (5) IN A TRANSACTION THAT DOES NOT
REQUIRE REGISTRATION UNDER THE SECURITIES ACT BUT IS IN ACCORDANCE WITH APPLICABLE
STATE SECURITIES LAWS AND IN RELATION TO WHICH THE HOLDER HAS FURNISHED TO THE
COMPANY AN OPINION TO SUCH EFFECT FROM COUNSEL OF RECOGNISED STANDING IN FORM AND
SUBSTANCE SATISFACTORY TO THE COMPANY PRIOR TO SUCH OFFER, SALE, PLEDGE OR TRANSFER.
THE HOLDER HEREOF, BY PURCHASING THIS SECURITY, REPRESENTS AND AGREES FOR THE
BENEFIT OF THE COMPANY THAT IT IS A NON-U.S. PERSON, AND ACKNOWLEDGES THAT HEDGING
TRANSACTIONS INVOLVING THESE SECURITIES MAY NOT BE CONDUCTED UNLESS CONDUCTED IN
COMPLIANCE WITH THE SECURITIES ACT.
 Sale; Assignment
 Exhibit A
  A-3




---



##### 



Representations of Holder
   Schedule B
  Capital Adjustments
    Governing Law
 Notices
 A-4




---



##### 



Holidays
 Lost Warrants
 Fractional Shares
 Headings
 [Signature page follows.]
 A-5




---



##### 



By:Name:Title:Attest:Name:Title:
 A-6




---



##### 



Exhibit A to Warrant
 
  [insert name of transferee]
       A-7




---



##### 



A.
    
    It is acquiring the Unit Securities for its own account or an account with respect to which
it exercises sole investment discretion and that it and any such account or person is not a
U.S. Person, and it is aware that the acquisition of Unit Securities is being made in reliance
on Regulation S under the Securities Act.B.
    
    It acknowledges that the Unit Securities have not been registered under the Securities Act
and may not be offered or sold except as provided below.C.
    
    It understands and agrees:
 1.
    
    that the Unit Securities are being offered only outside the United States to
non-U.S. Persons in an offshore transaction in reliance upon Regulation S under the
Securities Act; and2.
    
    that it shall not offer, sell, pledge or otherwise transfer any Unit Security
within six (6) months after the date of original issuance of such Unit Security or, in
the case of an affiliate (as defined in Rule 144 promulgated under the Securities Act) of
the Company, at any time until the later of (i) one (1) year after the date of original
issuance of such Unit Security and (ii) three months after it ceases to be an affiliate
of the Company, other than (in each case as indicated and certified by the transferor, in
the case of Primary Shares or Warrant Shares, in the Certificate of Transfer on the
reverse of the certificate representing such Primary Shares or Warrant Shares, and, in
the case of Warrants, in a certificate furnished by the transferor to the Company upon
request for transfer):
 (a)
    
    to the Company;(b)
    
    pursuant to an effective registration statement under the Securities Act
and in accordance with any applicable securities laws of any state of the United
States;(c)
    
    in an offshore transaction in accordance with Regulation S under the
Securities Act;(d)
    
    pursuant to an exemption from the registration requirements of the
Securities Act; or(e)
    
    in a transaction that does not require registration under the Securities
Act but is in accordance with applicable state securities laws and in relation to
which the transferor has furnished to the Company an opinion to such effect from
counsel of recognized standing in form and substance satisfactory to the Company
prior to such offer, sale, pledge or transfer.
 B-1




---



##### 



D.
    
    It understands that in any resale and transfer of Unit Securities it will, and each
subsequent holder thereof is required to, notify any purchaser of Unit Securities of the
resale restrictions referred to above, if then applicable. This notification requirement will
be satisfied by virtue of the fact that the following legend will be placed on the
certificates representing the Primary Shares, the Warrants and the Warrants Shares, unless
otherwise agreed to by the Company:
 THIS SECURITY HAS NOT BEEN AND WILL NOT REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR APPLICABLE STATE SECURITIES LAWS. THE HOLDER HEREOF, BY PURCHASING THIS
SECURITY, AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS SECURITY MAY NOT BE OFFERED, SOLD,
PLEDGED, OR OTHERWISE TRANSFERRED BY SUCH HOLDER PRIOR TO THE LATER OF THE (X) SIX MONTHS
FOLLOWING THE ISSUANCE HEREOF OR (Y) IF APPLICABLE, THREE MONTHS AFTER IT CEASES TO BE AN
AFFILIATE, OTHER THAN (1) TO THE COMPANY, (2) PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT UNDER THE SECURITIES ACT AND IN ACCORDANCE WITH ANY APPLICABLE LAWS OF ANY STATE
OF THE UNITED STATES, (3) IN AN OFFSHORE TRANSACTION COMPLYING WITH REGULATION S UNDER THE
SECURITIES ACT, (4) PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT
PROVIDED BY RULE 144, IF APPLICABLE, UNDER THE SECURITIES ACT OR (5) IN A TRANSACTION THAT
DOES NOT REQUIRE REGISTRATION UNDER THE SECURITIES ACT BUT IS IN ACCORDANCE WITH APPLICABLE
STATE SECURITIES LAWS AND IN RELATION TO WHICH THE HOLDER HAS FURNISHED TO THE COMPANY AN
OPINION TO SUCH EFFECT FROM COUNSEL OF RECOGNISED STANDING IN FORM AND SUBSTANCE
SATISFACTORY TO THE COMPANY PRIOR TO SUCH OFFER, SALE, PLEDGE OR TRANSFER. THE HOLDER
HEREOF, BY PURCHASING THIS SECURITY, REPRESENTS AND AGREES FOR THE BENEFIT OF THE COMPANY
THAT IT IS A NON-U.S. PERSON, AND ACKNOWLEDGES THAT HEDGING TRANSACTIONS INVOLVING THESE
SECURITIES MAY NOT BE CONDUCTED UNLESS CONDUCTED IN COMPLIANCE WITH THE SECURITIES ACT.
 E.
    
    It acknowledges that the foregoing restrictions apply to holders of beneficial interests in
the Unit Securities as well as to holders of Unit Securities.F.
    
    It acknowledges that it shall not engage in any hedging transactions involving the Unit
Securities unless in compliance with the Securities Act.G.
    
    It is a Qualified Investor within the meaning of Section 86 of the Financial Services and
Markets Act 2000 and an investment professional within the meaning of Article 19 of the FSMA
2000 (Financial Promotion) Order 2005.
 B-2