The promoting effect of antimony oxide addition on the catalytic performances of LaVO4 catalyst for catalyzing the selective oxidation of hydrogen sulfide to sulfur was studied. The multiphase La-V-Sb catalysts were characterized by temperature programmed reduction, X-ray diffraction, and Brunauer-Emmett-Teller techniques. A synergistic effect between the mixed metal oxides was observed which strongly increased the catalyst selectivity and the sulfur yield (the maximum yield increased from 88.5% for LaVO4 to 100% for La-V-Sb when weight hourly space velocity was 0.0244 mol of H2S/((g of catalyst)/h)). The best activity was observed for the La-V-Sb catalyst with V/Sb atomic ratio = 1.0. The improvements of catalytic performances were partly ascribed to the formation of SbVO4 species. The La-V-Sb catalysts showed a much wider temperature window for obtaining 100% sulfur yield than V-Sb and Mg-V-Sb catalysts. This was explained in terms of the better isolation of the active sites (caused by the large La3+ size) and the easier desorption of the elemental sulfur (caused by the lanthanum basicity).