Summary:Comparable results were obtained with a commercially available disposable system for the production of H2and CO2in an anaerobic jar (the Gaspak system) and with a standard anaerobic jar procedure. Both systems were used with the Baird&Tatlock anaerobic jar and a room temperature catalyst. The test organisms included strict anaerobes such asClostridium oedematienstype D andCl. tetani.Comparative tests were also made withBacteroidesspecies from laboratory stock cultures and with freshly isolated strains ofBacteroides.On occasion, higher recoveries were obtained with the standard system when relatively demanding models were set up but it has limitations, having been developed initially for research purposes. The Gaspak system probably gives more reliable and more reproducible results in a laboratory in which experience with strict anaerobes is limited or sporadic.