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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 /+PMFxGhP3EY2fWp2l6oBQ==

<SEC-DOCUMENT>0001144204-09-039775.txt : 20090731
<SEC-HEADER>0001144204-09-039775.hdr.sgml : 20090731
<ACCEPTANCE-DATETIME>20090731140019
ACCESSION NUMBER:		0001144204-09-039775
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090731
FILED AS OF DATE:		20090731
DATE AS OF CHANGE:		20090731

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Carlson Timothy C
		CENTRAL INDEX KEY:			0001392394

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-16239
		FILM NUMBER:		09976713

	MAIL ADDRESS:	
		STREET 1:		6 FRONWOOD ROAD
		CITY:			SANDY HOOK
		STATE:			CT
		ZIP:			06482

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ATMI INC
		CENTRAL INDEX KEY:			0001041577
		STANDARD INDUSTRIAL CLASSIFICATION:	INDUSTRIAL INORGANIC CHEMICALS [2810]
		IRS NUMBER:				061481060
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		7 COMMERCE DRIVE
		CITY:			DANBURY
		STATE:			CT
		ZIP:			06810-4169
		BUSINESS PHONE:		2037941100

	MAIL ADDRESS:	
		STREET 1:		7 COMMERCE DRVIE
		CITY:			DANBURY
		STATE:			CT
		ZIP:			06810-4169

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ATMI HOLDINGS INC
		DATE OF NAME CHANGE:	19970625
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form424418_073109135952-.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-07-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001041577</issuerCik>
        <issuerName>ATMI INC</issuerName>
        <issuerTradingSymbol>ATMI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001392394</rptOwnerCik>
            <rptOwnerName>Carlson Timothy C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>6 COMMERCE DR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DANBURY</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>US 06810</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-07-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18.2279</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>37817</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>/s/Timothy Carlson</signatureName>
        <signatureDate>2009-07-31</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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