The effects of metal oxide supports on ethanol oxidation have been investigated by drop coating Pt nanoparticles onto glassy carbon electrodes coated with thin layers of ruthenium oxide, tin oxide, a mixed Ru + Sn oxide, and onto an indium-tin oxide (ITO) electrode. All four oxide supports exhibited significant co-catalytic effects, with their effectiveness at low potentials increasing in the order Ru oxide < ITO < Ru + Sn oxide < Sn oxide. However, at higher potentials (e.g. 0.4V vs. SCE) currents were higher for Pt supported on Ru oxide or Ru + Sn oxide than on Sn oxide, revealing mechanistic differences between the roles of Ru and Sn oxide. Although Sn oxide produced very high initial activities, ITO and Ru +Sn oxide provided more stable performances. (C) 2012 Elsevier Ltd. All rights reserved.