The details of the preparation and characterization of co-deposited Pt/WO3 electrodes are presented. X-ray, scanning, and transmission electron microscopic studies revealed that WO3 is amorphous and that approximately 40 angstrom Pt crystallites are uniformly dispersed in the deposit. The influence of the deposition conditions and the effect of the solution acidity on the activity of such electrodes for methanol oxidation have been studied. The results demonstrated that the Pt/WO3 electrodes are much more active and more resistant to poisoning than Pt or Pt/Ru alloy catalysts. The reaction mechanism was studied by various electrochemical and surface analysis techniques. A reaction scheme that involves successive stepwise dehydrogenation of methanol, formation/oxidation of hydrogen tungsten bronze, and oxidation of organic intermediates and CO at the Pt/WO3 interface is proposed.