The oxidation of submonolayers of Ru and Sn on Pt in sulfuric acid was monitored with ellipsometry. In the presence of methanol the oxides on Ru and Sn disappear but the Pt-oxide is not affected by methanol. This signifies that Ru and Sn are present in their zero valent state during the methanol oxidation. DEMS measurements showed that both metals enhance methanol oxidation. The promoting role of these metals is explained with the bifunctional mechanism.