A Pt-WOx nanophase electrode showed a considerably more enhanced electrocatalytic activity than Pt itself for methanol oxidation and exactly the reverse change in optical signal intensity with respect to electrochemical cell potential, compared with an electrochromic WOx electrode. This provides evidence for hydrogen spillover from Pt to WOx. Consequently, it was possible to directly observe the in-situ hydrogen transfer from platinum to tungsten oxide in a fuel cell electrode using electrochromism. The transfer of hydrogen ions, produced on the platinum during the electrooxidation of methanol, to the tungsten oxide ensures that the active reaction sites on the platinum remain clean, thus enhancing the electrooxidation current density.