- Statement of Changes in Beneficial Ownership (4)

FORM 4 [ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0287 Expires: February 28, 2011 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(f) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * Flynn Frederick C JR	2. Issuer Name and Ticker or Trading Symbol ATMI INC [ ATMI ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __ X __ Director                      _____ 10% Owner _____ Officer (give title below)      _____ Other (specify below)
(Last)          (First)          (Middle) 6 COMMERCE DR	3. Date of Earliest Transaction (MM/DD/YYYY) 4/7/2010
(Street) DANBURY, CT US 06810 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) _ X _ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price

Table II - Derivative Securities Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Options	$28.86	4/7/2010		D   (1)			2842	(1)	1/3/2016	Common Stock	2842	(1)	0	D
Stock Options	$28.86	4/7/2010		A   (1)		2842		(1)	5/26/2015	Common Stock	2842	(1)	2842	D
Stock Options	$30.53	4/7/2010		D   (1)			3853	(1)	1/2/2017	Common Stock	3853	(1)	0	D
Stock Options	$30.53	4/7/2010		A   (1)		3853		(1)	5/26/2015	Common Stock	3853	(1)	3853	D
Stock Options	$31.29	4/7/2010		D   (1)			3563	(1)	1/2/2018	Common Stock	3563	(1)	0	D
Stock Options	$31.29	4/7/2010		A   (1)		3563		(1)	5/26/2015	Common Stock	3563	(1)	3563	D
Stock Options	$13.82	4/7/2010		D   (1)			6477	(1)	2/11/2019	Common Stock	6477	(1)	0	D
Stock Options	$13.82	4/7/2010		A   (1)		6477		(1)	5/26/2015	Common Stock	6477	(1)	6477	D
Stock Options	$16.9	4/7/2010		D   (1)			6185	(1)	2/11/2020	Common Stock	6185	(1)	0	D
Stock Options	$16.9	4/7/2010		A   (1)		6185		(1)	5/26/2015	Common Stock	6185	(1)	6185	D

Explanation of Responses:

( 1)

The reported transactions involve the amendment of five outstanding option grants, resulting in the deemed cancellation for SEC disclosure purposes, of the "old" option and the grant of a replacement option. The amendments extend the term of the options for a five year period from Mr. Flynn's departure from the Board of Directors. The option originally granted on February 11, 2010 was also amended to accelerate vesting such that it is fully vested on May 26, 2010. All other options were already fully vested.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Flynn Frederick C JR 6 COMMERCE DR DANBURY, CT US 06810	X

Signatures
/s/Douglas Neugold,atty-in-fact		4/9/2010
** Signature of Reporting Person		Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
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