UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934 (Amendment No. )

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o | Definitive Proxy Statement
x | Definitive Additional Materials
o | Soliciting Material under §240.14a-12
CDTI ADVANCED MATERIALS, INC.
(Name of Registrant as Specified In Its Charter)
(Name of Person(s) Filing Proxy Statement, if other than the Registrant)
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*** Exercise Your Right to Vote *** Important Notice Regarding the Availability of Proxy Materials for the Stockholder Meeting to Be Held on August 24, 2018 CDTI ADVANCED MATERIALS INC Date: August 24, 2018 Time: 10:00 AM PDT 1700 Fiske Place You are receiving this communication because you hold shares in the above named company. This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side). We encourage you to access and review all of the important information contained in the proxy materials before voting. 1234567 1234567 Envelope # # of # Sequence # 1 OF 2 12 15 0000385269_1 R1.0.1.17 Broadridge Internal Use Only Job # Sequence # See the reverse side of this notice to obtain proxy materials and voting instructions. CDTI ADVANCED MATERIALS, INC. 1700 FISKE PLACE OXNARD, CA 93033 Investor Address Line 1 Investor Address Line 2 Investor Address Line 3 Investor Address Line 4 Investor Address Line 5 John Sample 1234 ANYWHERE STREET ANY CITY, ON A1A 1A1 1234567 1234567 1234567 234567 Meeting Information Meeting Type: Annual Meeting For holders as of: June 29, 2018 Location: CDTI Advanced Materials, Inc Oxnard, CA 93033 B A R C O D E

Before You Vote How to Access the Proxy Materials Proxy Materials Available to VIEW or RECEIVE: Have the information that is printed in the box marked by the arrow (located on the by the arrow (located on the following page) in the subject line. How To Vote Please Choose One of the Following Voting Methods marked by the arrow available and follow the instructions. Only 0000385269_2 R1.0.1.17 Vote In Person: Many stockholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares. Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the box Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. Internal Use 1. Notice & Proxy Statement2. Form 10-K How to View Online: following page) and visit: www.proxyvote.com. How to Request and Receive a PAPER or E-MAIL Copy: If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request: 1) BY INTERNET:www.proxyvote.com 2) BY TELEPHONE:1-800-579-1639 3) BY E-MAIL*:sendmaterial@proxyvote.com * If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before August 12, 2018 to facilitate timely delivery.

The Board of Directors recommends you vote FOR the following: 1. To elect four (4) Directors to hold office until the next annual meeting. Nominees 01 Matthew Beale 02 Bob Ching 03 Lon E. Bell, Ph.D. 04 Martin S. McDermut The Board of Directors recommends you vote FOR proposals 2, 3 and 4. 2. To ratify the appointment of Rose Snyder & Jacobs, LLP as CDTI's independent registered public accounting firm for the 2018 fiscal year; 3. To conduct, a non-binding advisory vote to approve the compensation of the Company's named executive officers; and 4. To approve an amendment to the corporation's Restated Certificate of Incorporation, as amended, to effect a reverse stock split of outstanding shares of common stock by a ratio determined in the sole discretion of the Board of Directors. NOTE: To transact any other business that may properly come before the Annual Meeting or any adjournments or postponements of the Annual Meeting. xxxxxxxxxx Cusip Envelope # # of # Sequence # 0000385269_3 R1.0.1.17 Broadridge Internal Use Only xxxxxxxxxx Job # Sequence # B A R C O D E 23456789012 2 2 2 2 12345678901 12345678901 12345678901 12345678901 12345678901 12345678901 12345678901 12345678901 12345678901 12345678901 Voting items

THE COMPANY NAME INC. - CLASS A THE COMPANY NAME INC. - CLASS C 123,456,789,012.12345 123,456,789,012.12345 THE COMPANY NAME INC. - CLASS F 123,456,789,012.12345 Envelope # # of # Sequence # 0000385269_4 R1.0.1.17 Broadridge Internal Use Only THIS SPACE RESERVED FOR SIGNATURES IF APPLICABLE Job # Sequence # NAME THE COMPANY NAME INC. - COMMON 123,456,789,012.12345 THE COMPANY NAME INC. - CLASS B123,456,789,012.12345 THE COMPANY NAME INC. - CLASS D123,456,789,012.12345 THE COMPANY NAME INC. - CLASS E123,456,789,012.12345 THE COMPANY NAME INC. - 401 K123,456,789,012.12345 Reserved for Broadridge Internal Control Information