Exhibit 23.04 CONSENT OF INDEPENDENT AUDITORS As independent public accountants, we hereby consent to the incorporation of our reports included in this Form 10-K, into ATMI Inc.'s previously filed Registration Statement File Nos. 33-77060, 33-93048, 333-49561, 333-49561, 333- 56349, 333-55827, 333-82089 and 333-94641. We also consent to the application of our reports to the schedule labeled "Valuation and Qualifying Accounts" as of the dates and period covered by our reports. Rath, Anders, Dr. Wanner & Partner Munich, Germany March 28, 2000 /s/ Kabisch Dipl. -Kfm. Kabisch Vereidigter Buchprufer /s/ Metzler Dipl. -Kfm. Metzler Wirtschaftsprufer