The petrol and diesel combustion in motors produces sulfur and nitrogen oxides, they are the precursors of acid rain. Unfortunately, the Mexican fuel shows high-sulfur content; this concentration should be reduced to 50 ppmw or lower in order to achieve the international regulations. The Oxidative desulfurization (OD) is an alternative to obtain it. In this work, we propose a theoretical reaction mechanism for the OD; this pathway is carried out through a combination of the molibdate anion, the hydrogen peroxide and several dibenzothiophenes by Density Functional Theory (DFT) using the B3LYP functional and the DGDZVP double zeta basis. The results show that the energy of the determinant step of the reaction is lower than the experimental amount obtained without catalyst. Finally, the environment provided by water molecules is important for decreasing the reaction mechanism energy.