Electrocatalytic oxidation of ethylene glycol on platinum-gold nanocomposite catalysts is investigated by cyclic voltammetry. Platinum-gold nanoparticles are prepared by chemical reduction, and cyclic voltammograms of carbon-supported platinum-gold nanocomposite catalysts show significant differences in alkaline, neutral and acidic solutions. The catalysts exhibit high electrocatalytic activity and stability in alkaline solution, showing oxidation peaks at low potentials with high current densities. Oxidation peaks at higher potentials with significant current declines are observed in neutral solution, and further positive shifts in peak potential are observed in acidic solution. The concentrations of ethylene glycol and the supporting electrolytes also affect the reaction. A higher alkaline concentration is favorable for oxidation at low potential with high current density. Increased phosphate concentration in neutral buffer solution yields a negative shift in peak potential and minor enhancement in peak current density. Changes in the sulfuric acid concentration mainly affect peak current density. Factors such as the synergic catalysis effect and increased active surface area are thought to be responsible for the reactivity of the platinum-gold nanocomposite catalysts. (C) 2009 Elsevier Ltd. All rights reserved.