Supported molybdenum catalysts were prepared by wet impregnation of acidic solutions of oxalic acid and ammonium heptamolibdate at pH=0 on γ-alumina, with theoretical metal loadings of: 0.8, 1.0, 1.7 and 2.5 Mo atoms/nm². The catalysts were used in the oxidative desulfurization (ODS) process in order to evaluate the catalytic performance of cumene hidroperoxide (CHP) as oxidant agent. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX) and temperature-programmed reduction (TPR). Catalytic activity results were discussed in terms of the oxidant products of DBT and its alkyl-substitued (4-MDBT and 4,6-DMDBT). Results showed high reactivity of CHP as oxidant in the ODS process and that activity is due to two contributions: the heterogeneous catalytic reaction and the homogeneous non-catalytic reaction, the last one being important.