Methanol was strongly adsorbed on ZrO2 support as dioxymethylene and carbonate species, both of which were adsorbed on the basic sites as the intermediate for complete oxidation. On the molybdenum oxide monolayer, it was adsorbed as methoxide species to form formaldehyde. Upon elevating the temperature, however, the methoxide species turned into formate ion, from which CO was finally desorbed. Adsorption of methoxide species readily takes place only on the loaded molybdenum oxide monolayer, and the acid sites seem to accommodate the species.