The activity of unsupported ternary PtRuMeOx (Me = W, Mo, V) high surface area catalysts towards methanol oxidation under fuel cell relevant conditions, at constant potential and elevated temperature of 60 degreesC, was investigated by the thin-film electrode method. CO-stripping experiments for actual surface area detection, using differential electrochemical mass spectrometry (DEMS) to evaluate the amount of adsorbed CO, show that the electrochemically active area of the particle surface is significantly smaller than the total particle surface area determined by N-2 BET measurements, indicating that part of their surface consists of MeOx. The specific surface activity of the catalysts towards methanol oxidation at 60 degreesC, normalized to the current density per square centimeter of electrochemically active noble metal surface, decreases in the order PtRuVOx > PtRuMoOx > PtRu > PtRuWOx = PtRu (E-TEK). Apparently, the surface oxide leads to an acceleration of the methanol oxidation reaction, which is, however, partly compensated by a decrease in active surface area.