The catalytic activities for H₂O₂ generation using gaseous H₂ and O₂ have been examined and compared over various type of zeolites such as Beta, Y, USY, L and MCM-41. The feed ratio of H₂ : O₂ = 1 : 1 is found to lead to the optimal H₂O₂ production. In the case of H-zeolites, a zeolite Beta-supported Pd catalyst and a zeolite USY-supported Pd catalyst exhibit higher activities than the other zeolite- supported catalysts. On the other hand, in the case of Na or K form zeolites a zeolite USY-supported Pd catalyst shows the highest activity. Comparatively, a Na or K form zeolite-supported Pd catalyst is more active than a H form zeolite-supported Pd catalyst. In all cases, the production of H₂O₂ is found to increase obviously with increasing reaction time.