Electrochemical oxidation of methanol on Pt/C and Pt-Ru/C electrocatalysts was studied by slow scan rate voltammetry at 130-190 degrees C. The effects of partial pressures of water, methanol, and CO on the methanol electrooxidation rate were determined. It was found that methanol oxidation on Pt-Ru/C proceeds primarily via the "indirect" route through the formation of strongly adsorbed intermediate COads, while on Pt methanol electrooxidation occurs primarily via "direct" route through the formation of weakly adsorbed intermediates. At 140 degrees C activity of Pt-Ru/C in methanol electrooxidation was found 2 orders of magnitude higher than that of Pt/C. Methanol oxidation reaction orders per water and methanol vapor pressures were determined. The main features of methanol electrooxidation both on Pt and Pt-Ru were accounted for assuming Langmuir-Hinshelwood mechanism of respective RDS. (C) 2012 Elsevier B.V. All rights reserved.