Selective oxidation of H2S to elemental sulfur was studied using the Cu-V and Cu-V-Mo mixed oxide catalysts with different O-2/H2S ratios between 0 and 3. High activities and high sulfur selectivities reaching 0.98 were obtained with the Cu-V catalyst. The Cu-V-Mo mixed oxide catalyst showed higher activity with a somewhat less selectivity. The Cu-V catalyst, which was originally in the form of alpha-Cu2V2O7, was converted to Cu3VS4, CuS and VOx during the initial stages of reaction. Oxidized form of the catalyst resulted in the formation of mostly SO2. Partially reduced catalyst containing V+2 and V+4 was highly selective for the production of elemental sulfur, which was produced by a series of redox reactions involving lattice oxygen. (C) 2004 Elsevier Ltd. All rights reserved.