The IR-spectroscopy analysis brought about the conclusion that methoxyl groups are formed on the surface of Ni-oxide during adsorption of methanol at 25 degrees C. Further on, they are oxidized partially to CO2 by surface active oxygen at temperatures 25-35 degrees C. O- forms (taking part in the oxidation process) are observed on the surface of the oxide. The methoxyl groups undergo a complete oxidation to form formiate complexes in the presence of oxygen in gaseous phase at temperatures higher than 35 degrees C. The latter give the products of complete oxidation - CO2 and H2O.