August 8, 2006 – ATMI Inc. directors have approved a $150 million expansion of its share repurchase program, doubling an existing plan set down last fall.

ATMI’s board previously approved a $75 million share repurchase plan in October 2005, and had used $54 million so far, funded primarily from cash generated from operations. As of June 30, the company had approximately 36.7 million shares outstanding and $2424 million in cash and marketable securities.

“Given our significant cash balance and confidence in our cash-generating business model, this expanded plan to repurchase shares is an attractive way to return a portion of our capital to shareholders,” stated Doug Neugold, company CEO.