<SUBMISSION>
<ACCESSION-NUMBER>0001193125-14-131321
<TYPE>8-K
<PUBLIC-DOCUMENT-COUNT>3
<PERIOD>20140404
<ITEMS>5.01
<ITEMS>9.01
<FILING-DATE>20140404
<DATE-OF-FILING-DATE-CHANGE>20140404
<FILER>
<COMPANY-DATA>
<CONFORMED-NAME>CLEAN DIESEL TECHNOLOGIES INC
<CIK>0000949428
<ASSIGNED-SIC>3564
<IRS-NUMBER>061393453
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<FILING-VALUES>
<FORM-TYPE>8-K
<ACT>34
<FILE-NUMBER>001-33710
<FILM-NUMBER>14745221
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>4567 TELEPHONE ROAD
<STREET2>SUITE 100
<CITY>VENTURA
<STATE>CA
<ZIP>93003
<PHONE>805 639 9458
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>4567 TELEPHONE ROAD
<STREET2>SUITE 100
<CITY>VENTURA
<STATE>CA
<ZIP>93003
</MAIL-ADDRESS>
</FILER>
<DOCUMENT>
<TYPE>8-K
<SEQUENCE>1
<FILENAME>d706923d8k.htm
<DESCRIPTION>FORM 8-K
<TEXT>
<HTML><HEAD>
<TITLE>Form 8-K</TITLE>
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 <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>UNITED STATES </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SECURITIES AND EXCHANGE COMMISSION </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>WASHINGTON, D.C. 20549 </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>FORM&nbsp;8-K
</B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>CURRENT REPORT </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Pursuant
to Section&nbsp;13 or 15(d)&nbsp;of the </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Securities Exchange Act of 1934 </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Date of report (Date of earliest event reported): April&nbsp;4, 2014 </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:24pt; font-family:Times New Roman" ALIGN="center"><B>CLEAN DIESEL TECHNOLOGIES, INC. </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Exact Name of Registrant as Specified in Charter) </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top" ALIGN="center"><B>Delaware</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"><B>001-33710</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"><B>06-1393453</B></TD></TR>
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<TD VALIGN="top" ALIGN="center"><B>(State or Other Jurisdiction&nbsp;<BR>of Incorporation)</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Commission</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>File Number)</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"><B>(I.R.S. Employer&nbsp;<BR>Identification No.)</B></TD></TR>
</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>4567 Telephone Road, Suite 100 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Ventura, California, 93003 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Address of Principal Executive Offices) (Zip Code) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(805) 639-9458 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Registrants telephone number, including area code) </B></P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Former name or former address, if changed since last report) </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Check the appropriate box below if the Form&nbsp;8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the
following provisions: </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></TD>
<TD ALIGN="left" VALIGN="top">Written communications pursuant to Rule&nbsp;425 under the Securities Act (17 CFR 230.425) </TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></TD>
<TD ALIGN="left" VALIGN="top">Soliciting material pursuant to Rule&nbsp;14a-12 under the Exchange Act (17 CFR 240.14a-12) </TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></TD>
<TD ALIGN="left" VALIGN="top">Pre-commencement communications pursuant to Rule&nbsp;14d-2(b)&nbsp;under the Exchange Act (17 CFR 240.14d-2(b)) </TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></TD>
<TD ALIGN="left" VALIGN="top">Pre-commencement communications pursuant to Rule&nbsp;13e-4(c)&nbsp;under the Exchange Act (17 CFR 240.13e-4(c)) </TD></TR></TABLE> <P STYLE="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;5.01 Other Events. </B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">On April&nbsp;4, 2014, Clean Diesel Technologies, Inc. closed a registered direct offering of 2,030,000 shares of common stock and warrants to
purchase 812,000 shares of common stock for gross proceeds of $6,902,000. The shares of common stock and warrants were sold in units, with each unit consisting of one share of common stock and 0.4 of one five and a half-year warrant to purchase one
share of common stock at an exercise price of $4.20 per share. The offering was previously announced in a Current Report on Form 8-K filed on April&nbsp;1, 2014 and a press release furnished therewith. </P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;9.01 Financial Statements and Exhibits. </B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(d)&nbsp;Exhibits. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="bottom" NOWRAP ALIGN="center"> <P STYLE="border-bottom:1.00pt solid #000000; width:55.75pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Exhibit&nbsp;Number</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" NOWRAP> <P STYLE="border-bottom:1.00pt solid #000000; width:78.55pt; font-size:8pt; font-family:Times New Roman"><B>Description of Exhibits</B></P></TD></TR>


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<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;5.1</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Opinion of DLA Piper LLP (US)</TD></TR>
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<TD VALIGN="top" NOWRAP>23.1</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Consent of DLA Piper LLP (US) (included in Exhibit 5.1)</TD></TR>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>SIGNATURES </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by
the undersigned hereunto duly authorized. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="bottom"><FONT STYLE="font-size:8pt">&nbsp;</FONT></TD>
<TD VALIGN="bottom" COLSPAN="5"><B>CLEAN DIESEL TECHNOLOGIES, INC.</B></TD></TR>
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<TD VALIGN="top">April&nbsp;4, 2014</TD>
<TD VALIGN="bottom"><FONT STYLE="font-size:8pt">&nbsp;</FONT></TD>
<TD VALIGN="bottom">By:</TD>
<TD VALIGN="bottom"><FONT STYLE="font-size:8pt">&nbsp;</FONT></TD>
<TD VALIGN="bottom" COLSPAN="3"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/&nbsp;Nikhil A. Mehta</P></TD></TR>
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<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT STYLE="font-size:8pt">&nbsp;</FONT></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"><FONT STYLE="font-size:8pt">&nbsp;</FONT></TD>
<TD VALIGN="top">Name:</TD>
<TD VALIGN="bottom"><FONT STYLE="font-size:8pt">&nbsp;</FONT></TD>
<TD VALIGN="top">Nikhil A. Mehta</TD></TR>
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<TD VALIGN="bottom"><FONT STYLE="font-size:8pt">&nbsp;</FONT></TD>
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<TD VALIGN="top">Title:</TD>
<TD VALIGN="bottom"><FONT STYLE="font-size:8pt">&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Member of the Interim Office of the Chief</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Executive Officer and Chief Financial Officer</P></TD></TR>
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<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>d706923dex51.htm
<DESCRIPTION>EX-5.1
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>Exhibit 5.1 </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<IMG SRC="g706923g70o00.jpg" ALT="LOGO">
</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
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<TD VALIGN="bottom"><B>DLA Piper LLP (US)</B></TD></TR>
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<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman">2525 East Camelback Road, Suite</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman">1000</P></TD></TR>
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<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
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<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman">Phoenix, Arizona 85016-4232</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman">www.dlapiper.com</P></TD></TR>
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<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
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<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">T&nbsp;480.606.5100</TD></TR>
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<TD VALIGN="top"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
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<TD VALIGN="bottom">F &nbsp;480.606.5101</TD></TR>
</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">April&nbsp;4, 2014 </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Clean Diesel Technologies, Inc. </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">4567 Telephone Road, Suite 100
</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Ventura, California 93003 </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left">Re:</TD>
<TD ALIGN="left" VALIGN="top"><U>Clean Diesel Technologies, Inc. &#150; Common Stock and Warrants</U> </TD></TR></TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Ladies and Gentlemen: </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">We have acted as counsel to Clean Diesel Technologies, Inc., a Delaware corporation (the &#147;<B><I>Company</I></B>&#148;), in connection
with the Company&#146;s sale of 2,030,000 shares of the Company&#146;s Common Stock, par value $0.01 per share (the &#147;<B><I>Common Stock</I></B>&#148;), and warrants (the &#147;<B><I>Warrants</I></B>&#148;) to initially purchase up to an
aggregate of 812,000 shares (the &#147;<B><I>Warrant Shares</I></B>&#148;) of the Company&#146;s Common Stock, pursuant to the Placement Agent Agreement, dated April&nbsp;1, 2014, by and among Roth Capital Partners, LLC and Craig-Hallum Capital
Group LLC, as placement agents, and the Company and the Subscription Agreements, dated April&nbsp;1, 2014, between the investors named therein and the Company. The Common Stock and the Warrant Shares are referred to herein as the &#147;<B><I>Equity
Securities</I></B>&#148; and the Warrants and the Equity Securities are referred to herein as the &#147;<B><I>Securities</I></B>.&#148; The Securities were registered by the Company with the Securities and Exchange Commission (the
&#147;<B><I>Commission</I></B>&#148;) on the shelf registration statement on Form S-3 (No. 333-181443) filed on May&nbsp;15, 2012 by the Company with the Commission pursuant to the Securities Act of 1933, as amended (the &#147;<B><I>Securities
Act</I></B>&#148;) and declared effective on May&nbsp;21, 2012 (the &#147;<B><I>Registration Statement</I></B>&#148;), including the base prospectus, dated May&nbsp;21, 2012, as supplemented by a prospectus supplement (the
&#147;<B><I>Prospectus</I></B>&#148;), dated April&nbsp;1, 2014, filed by the Company with the Commission pursuant to Rule 424(b) of the General Rules and Regulations under the Securities Act (the &#147;<B><I>Rules and Regulations</I></B>&#148;).
The Registration Statement relates to, among other things, the issuance and sale by the Company, from time to time pursuant to Rule 415 of the Rules and Regulations, of $50,000,000 of various securities of the Company, including Common Stock and
Warrants. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">This opinion is being furnished in accordance with the requirements of Item&nbsp;601(b)(5) of Regulation S-K under the
Securities Act. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">In rendering the opinions stated herein, we have examined and relied upon the following: </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(i) the Registration Statement; </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(ii) the Amended and Restated Certificate of Incorporation of the Company, as certified by the Secretary of the State of Delaware and as
certified by the Secretary of the Company (the &#147;<B><I>Certificate of Incorporation</I></B>&#148;); </P>

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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Clean Diesel Technologies, Inc. </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">April 4, 2014 </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Page 2 </P>
<p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>
 <P STYLE="margin-top:0pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(iii) the Amended and Restated By-laws of the Company, as currently in effect and as
certified by the Secretary of the Company; </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(iv) a copy of certain resolutions of the board of directors of the Company relating to the
registration and sale of the Securities, as certified by the Secretary of the Company; </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(v) a copy of certain resolutions of a committee
of the Board of Directors relating to the registration and sale of the Securities, as certified by the Secretary of the Company; and </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(vi)
the form of Warrant. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">We have also examined originals or copies, certified or otherwise identified to our satisfaction, of such records of
the Company and such agreements, certificates and receipts of public officials, certificates of officers or other representatives of the Company and others, and such other documents as we have deemed necessary or appropriate as a basis for the
opinions stated below. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">In our examination, we have assumed the genuineness of all signatures, including endorsements, the legal capacity
and competency of all natural persons, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as facsimile, electronic, certified, conformed or photostatic copies and the
authenticity of the originals of such copies. In making our examination of executed documents or documents to be executed, we have assumed that the parties thereto, other than the Company, will have been duly organized and be validly existing in
good standing, had or will have the power, corporate or otherwise, to enter into and perform all obligations thereunder and have also assumed the due authorization by all requisite action, corporate or other, and the execution and delivery by such
parties of such documents, and, as to parties other than the Company, the validity and binding effect thereof on such parties. In addition, we have assumed that the issuance and sale of the Securities do not, violate, conflict with or constitute a
default under (i)&nbsp;any agreement or instrument to which the Company is subject (other than the Placement Agent Agreement, the Subscription Agreements or the Warrants), (ii)&nbsp;any law, rule or regulation to which the Company is subject (other
than Opined on Law, as defined below), (iii)&nbsp;any judicial or regulatory order or decree of any governmental authority (other than those under Opined on Law) or (iv)&nbsp;any consent, approval, license, authorization or validation of, or filing,
recording or registration with, any governmental authority (other than those under Opined on Law). As to any facts relevant to the opinions stated herein that we did not independently establish or verify, we have relied upon oral or written
statements and representations of officers and other representatives of the Company and others and of public officials. We have also assumed that, upon issuance of any Equity Securities subsequent to the date hereof, the total number of shares of
Common Stock of the Company issued and outstanding will not, after giving effect to the issuance of such Equity Securities, exceed the total number of shares of Common Stock that the Company is authorized to issue under its Certificate of
Incorporation in effect at such time. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">We do not express any opinion with respect to the laws of any jurisdiction other than (i)&nbsp;the
General Corporations Law of the State of Delaware (the &#147;<B><I>DGCL</I></B>&#148;) and (ii)&nbsp;the laws of the State of New York, and to the extent that judicial or regulatory orders or decrees or consents, approvals, licenses, authorizations,
validations, filings, recordings or registrations with governmental authorities are relevant, to those required under such laws (all of the foregoing </P>

<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">


 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Clean Diesel Technologies, Inc. </P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">April 4, 2014 </P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Page 3 </P>
<p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P>
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">
being referred to as &#147;<B><I>Opined on Law</I></B>&#148;). We do not express any opinion with respect to the laws of any jurisdiction other than Opined on Law or as to the effect of any
non-Opined on Law on the opinions stated herein. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Our opinions stated herein are limited by applicable bankruptcy, insolvency,
reorganization, moratorium, fraudulent transfer, preference and other similar laws affecting creditors&#146; rights generally, and by general principles of equity (regardless of whether enforcement is sought in equity or at law). </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Based upon the foregoing and subject to the limitations, qualifications, exceptions and assumptions stated herein, we are of the opinion that:
</P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">1. The shares of Common Stock have been duly authorized and, when issued and sold upon payment therefor in the manner contemplated by the
Registration Statement and the Prospectus, will be validly issued, fully paid and non-assessable. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">2. The Warrants have been duly
authorized and, when executed, registered and delivered and paid for in the manner contemplated by the Registration Statement and the Prospectus, will constitute valid and legally binding obligations of the Company, enforceable against the Company
in accordance with their terms. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">3. The Warrant Shares have been duly authorized and, upon issuance, delivery and payment therefore upon
valid exercise of the Warrants in accordance with the terms of the Warrants, will be validly issued, fully paid and non-assessable. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">We
hereby consent to the filing of this opinion with the Commission. In giving this consent, we do not thereby admit that we are within the category of persons whose consent is required under Section&nbsp;7 of the Securities Act or the Rules and
Regulations. This opinion is expressed as of the date hereof unless otherwise expressly stated, and we disclaim any undertaking to advise you of any subsequent changes in the facts stated or assumed herein or of any subsequent changes in applicable
laws. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><DIV ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">


<TR>
<TD WIDTH="100%"></TD></TR>


<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">Very truly yours,</TD></TR>
<TR>
<TD HEIGHT="16"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">/s/ DLA Piper LLP (US)</TD></TR>
<TR>
<TD HEIGHT="16"></TD></TR>
<TR STYLE="font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"><B>DLA PIPER LLP (US)</B></TD></TR>
</TABLE></DIV>
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