A comparative study was conducted to assess the reactive adsorption of nitromethane on the surface of MgO-(100) and CaO(100) molecules. A calculated ab initio cluster model was used to evaluate the catalytic action of basic oxides on deprotonation. The adsorption sites of nitromethane and of the derivatives influencing the reaction were determined and their respective energies compared. Hydrogen-bonded intermediate states have been observed and shown to play a decisive role in the reactivity of the two substrates.