The influence of hydrogen deliberately occluded (absorbed) into a Pd electrode coated with a PdPtRu catalyst on the electrochemical oxidation of methanol in an acidic medium is reported. It was found that it is possible to oxidize methanol at very low potentials in the presence of occluded hydrogen, where control experiments showed insignificant activity. This indicates a strong diminution of poisoning of the electrode by adsorbed CO. The consumption of hydrogen during the electro-oxidation of methanol was much less than 0.6 mol of H per mol of oxidized methanol, indicating that the occluded hydrogen has a catalytic effect. Formaldehyde production was found to be lower than at a hydrogen-free electrode. (C) 2005 The Electrochemical Society.