We have studied the minimum energy pathway for the dimethyl sulfoxide reduction on silicene substrates. Starting with a configuration in which the molecule and the substrate are not interacting, the dimethyl sulfide molecule is physisorbed on the silicene as a first step, until it is finally reduced with the formation of silicene oxide units. As the reaction proceeds, the system gains energy, favoring the reduction of the molecule. The energy barrier for the reaction to proceed forward is 0.20 eV, which is 0.30 eV lower than the energy barrier for desorption. At the maximum coverage of 1/4 monolayer, silicene oxide lines are formed. These results pave the way to use silicene as a substrate to reduce dimethyl sulfoxide (a molecule with low dose toxicity) to dimethyl sulfide, an important compound in the global ecosystem cycle. In the final state, the DMS molecule is physisorbed on silicene oxide. Therefore, this reaction is also a viable and efficient mechanism for oxidation of silicene.