Catalytic recombination of hydrogen and oxygen as radiolysis gases was studied using ceramic blocks of cellular structure as a catalyst support. The characteristics of the catalyst samples obtained were compared to those of the presently used granulated catalyst RK-102-12 (OPK-2). The possibility of preventing the transition of the catalytic recombination of hydrogen and oxygen to the flame combustion mode by making a catalyst with "gradient" activity was examined. The results obtained confirm good prospects for using the cellular ceramic as a catalyst support for passive hydrogen recombiners to ensure hydrogen safety at nuclear power plants.