Nitric oxide inhibits methanol oxidation and leads to the formation of formaldehyde in automotive catalysts. A kinetic study has been experimentally carried out to determine the reaction mechanism in the CH3 OH-O2 -NO system. The surface coverage with NO was also measured for the used catalyst. The experimental results showed that both O2 and NO were adsorbed on the catalyst and acted as oxidizers, but the rate of methanol oxidation reaction with NO was two orders of magnitude less than that with O2. Consequently, the overall reaction rate decreases with increases in the NO adsorption on a catalyst surface.