Abstract: A gas stream containing hydrogen sulfide is combusted in a furnace to form a gas having a hydrogen sulfide to sulfur dioxide ratio of at least three to one. The gas is contacted with a conventional Claus catalyst to form elemental sulfur, which is separated and removed. The remaining gas is combined with an oxidizing gas stream and contacted with a special catalyst. The special catalyst has an active ingredient comprising a mixture of metal oxides or a mixed metal oxide, where metal is defined as at least two of the transition metals occurring in the first transition group of the periodic table. The special catalyst preferably has a spinel structure. As an option, a portion of the acid gas feed can be bypassed a point before the final reactor to ensure that the gas going to the final reactor promotes the desired catalytic action. The special catalyst oxidizes both COS and CS.sub.2 to CO.sub.2 and SO.sub.2, and converts H.sub.2 S and SO.sub.2 to elemental sulfur and water.