Oxidative desulfurization of model compounds (benzothiophene, dibenzothiophene, 4,6-dimethyldibenzo-thiophene) with hydrogen peroxide/acetic acid using polyoxometalates as catalysts has been studied. The tetrabutylammonium salts of [W6O19](2-), [V(VW11)O-40](4-), [PVW11O40](4-), and [PV2Mo10O40](4-) were prepared, and their activities were compared with (VO)(2)P2O7. The experimental results show that the highest active catalyst is [V(VW11)O-40](4-). The method was also used for the treatment of gas oil. The combination of solvent extraction and alumina adsorption can efficiently separate sulfone products. The resulting oil contained less than 0.055% sulfur, and this corresponds to 90% removal.