Ruthenium-oxide nanosheet (RuO 2 ns) crystallites with thickness less than 1nm were prepared via chemical exfoliation of a layered potassium ruthenate and deposited onto carbon supported platinum (Pt/C) as a potential co-catalyst for fuel cell anode catalysts. The electrocatalytic activity towards carbon monoxide and methanol oxidation was studied at various temperatures for different RuO 2 ns loadings. An increase in electrocatalytic activity was evidenced at temperatures above 40°C, while little enhancement in activity was observed at room temperature. The RuO 2 ns modified Pt/C catalyst with composition of RuO 2 :Pt=0.5:1 (molar ratio) exhibited the highest methanol oxidation activity. CO-stripping voltammetry revealed that RuO 2 ns promotes oxidation of adsorbed CO on Pt. In addition to the enhanced initial activity, the RuO 2 ns modified Pt/C catalyst exhibited improved stability compared to pristine Pt/C against consecutive potential cycling tests.