Oxidative desulfurization (ODS) of a synthetic diesel was carried out at mild conditions (atmospheric pressure and 60 degrees C) in presence of V2O5/ Al2O3 and V2O5/TiO2 catalysts. Two main aspects were studied: the effect of the oxidant reagent and the presence of nitrogen compounds on ODS of benzothiophenic compounds prevailing in diesel, such as benzothiophene, dibenzothiophene and alkyl substituted in positions 4 and 6. Results show that activity is improved when using hydrogen peroxide, as oxidant reagent, and V2O5/Al2O3, as catalyst. This result was attributed to the high decomposition of peroxide due to the presence of catalyst. In presence of nitrogen compounds, the ODS activity decreases in the order: quinoline > indole > carbazole. In order to explain this effect, successive chemisorption of DBT and quinoline on V2O5/Al2O3 catalyst was evaluated by FT-IR, and the results show that DBT is displaced by quinoline, occupying the adsorption sites of catalyst. N-compound effect could be explained by strong adsorption of nitrogen compounds on catalytic sites. (C) 2006 Elsevier B.V. All rights reserved.