The electrochemical oxidation of methanol, ethanol, n-propanol and n-butanol has been carried out at the Pt(111) and the stepped Pt(755) and Pt(332) surfaces in sodium hydroxide solution, Special attention was paid to the study of the oxygen-containing species generated and adsorbed during surface oxidation. The existence of reversible OHad, irreversible OHad and PtO species was suggested in the potential region relevant for the alcohol oxidation. The role of these species in the reaction was determined and a dual path mechanism was proposed for the alcohols studied.