Ruthenium-oxide nanosheet (RuO(2)ns) crystallites with thickness less than 1 nm 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 degrees C, while little enhancement in activity was observed at room temperature. The RuO(2)ns modified Pt/C catalyst with composition of RuO2: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. (C) 2009 Elsevier Ltd. All rights reserved.