A comparative study of methanol oxidation on a Pt(lll) surface was carried out in bicarbonate, carbonate and different pH values of sodium hydroxide solutions. The surface activity was directly correlated to the OHad species coverage. It was shown that the ’poisoning species’, produced in methanol oxidation, participate in the reaction although they partially block the surface, particularly at lower potentials. A dual path reaction mechanism, common to all alkaline solutions used, was proposed. It was based on the assumptions that HCO is a reactive intermediate and that formate is a reaction product in the main path, while CO2 is a product of ’poisoning species’ oxidation in st parallel reaction path.