Abstract: A container for radioactive material includes therein a catalyst device for catalyzing the recombination of gaseous hydrogen and oxygen in the container to give water, e.g. in a storage vessel for radioactive material. The device comprises a substrate in the form of at least one metal member (e.g. stainless steel) carrying a thermally sprayed low surface area ceramic coating (e.g. plasma sprayed alumina) which carries a high surface area ceramic coating (e.g. alumina from a sol), which latter coating carries catalytically active material (e.g. Pt metal), the catalyst having an outer, hydrophobic gas permeable coating (e.g. polysiloxane) for preventing the catalytically active material from contacting water.