SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
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                                    FORM 8-K

                                 CURRENT REPORT
                       PURSUANT TO SECTION 13 OR 15 (d) OF
                       THE SECURITIES EXCHANGE ACT OF 1934


         Date of Report (Date of earliest event reported): July 19, 2004

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                                   ATMI, INC.
             (Exact name of registrant as specified in its charter)

           Delaware                      1-16239                 06-1481060
(State or other jurisdiction of   (Commission file number)    (I.R.S. employer
 incorporation or organization)                              identification no.)


             7 Commerce Drive
            Danbury, Connecticut                                   06810
   (Address of principal executive offices)                      (Zip code)



       Registrant's telephone number, including area code: (203) 794-1100



                                   ATMI, INC.
                                    FORM 8-K
                                 CURRENT REPORT

                                TABLE OF CONTENTS

                                                                            Page
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Item 2.     Acquisition or Disposition of Assets..............................3

Item 7.     Exhibits..........................................................3

Signature.....................................................................4




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Item 2.       Acquisition or Disposition of Assets

      On July 20, 2004, ATMI, Inc., a Delaware corporation, issued a press
release announcing that it completed the previously announced sale of its
silicon epitaxial services business located in Mesa, Arizona, to International
Rectifier Corporation (NYSE: IRF), a world leader in power management
technology, for an aggregate purchase price of $41 million, subject to
adjustment as provided in the Asset Purchase Agreement (the "Agreement"), a copy
of which is filed as Exhibit 2.1 to this Current Report on Form 8-K.

      As set forth in the Agreement, the sale of the silicon epitaxial services
business, which consists of the line of business commonly known as "Epitronics"
or "Epi" which is generally engaged in the business of developing recipes for
and manufacturing of wafers coated with thin single or multiple layers of
silicon or SiGe epitaxy (the "Business"), which Business was operated through
Epitronics Corporation, a wholly-owned subsidiary of Advanced Technology
Materials, Inc. (collectively, the "Seller"), involved the sale of, among other
things, the following assets: (i) all real property described in the Agreement;
(ii) all inventories of raw materials, work-in-process, finished goods, products
under research and development, demonstration equipment, office and other
supplies, parts, packaging materials and other accessories related thereto,
which are used or held for use in the conduct of the Business; (iii) all
furniture, fixtures, equipment, machinery and other tangible personal property
used or held for use in the conduct of the Business; (iv) all leases or
subleases of tangible personal property described in the Agreement as to which
Seller is the lessor or sublessor and the leases of tangible personal property
described in the Agreement as to which Seller is the lessee or sublessee,
together with any options to purchase the underlying property; (v) all contracts
(other than the personal property leases) to which Seller is a party or under
which Seller has any rights or obligations and which relate to the conduct of
the Business; (vi) all prepaid expenses relating to the Business; (vii) all
intellectual property owned, licensed, used or held for use in the conduct of
the Business (including Seller's goodwill therein) and all rights, privileges,
claims, causes of action and options relating or pertaining to the Business or
the assets; (viii) all licenses (including applications therefor) utilized in
the conduct of the Business; (ix) all books and records reasonably used or held
for use in the conduct of the Business or otherwise relating to the assets sold
and used or held for use in the conduct of the Business; and (x) all other
assets and properties of Seller used or held for use in connection with the
Business except as otherwise provided in the Agreement.

Item 7.       Exhibits.

Exhibit No.  Description
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2.1 *        Asset Purchase Agreement dated as of June 28, 2004 entered into by
             and among IR Epi Services, Inc., International Rectifier
             Corporation, Advanced Technology Materials, Inc., and its
             wholly-owned subsidiary Epitronics Corporation.

99.1         Press Release, dated July 20, 2004, entitled "ATMI Completes Sale
             of Epitaxial Services to International Rectifier."

 * Portions omitted pursuant to a request for confidential treatment.




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                                    SIGNATURE

      Pursuant to the requirements of the Securities Exchange Act of 1934, ATMI,
Inc. has duly caused this report to be signed on its behalf by the undersigned
hereunto duly authorized.

Date: July 20, 2004

                                       ATMI, INC.


                                       By: /s/ Daniel P. Sharkey
                                          -------------------------------------
                                          Name:  Daniel P. Sharkey
                                          Title: Vice President, Treasurer and
                                                 Chief Financial Office




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