A facile, rapid, and wet-chemical co-reduction method is developed for synthesis of platinum@palladium core-shell nanoparticles supported on reduced graphene oxide (denoted as Pt@Pd/RGO) with the assistance of caffeine, without any seed or template. Caffeine is used here as a structure-directing agent and a capping agent, which is critical to the formation of Pt@Pd core-shell nanoparticles. Furthermore, the assynthesized Pt@Pd/RGO shows the enlarged electrochemically active surface area, remarkably enhanced catalytic activity, and improved stability for methanol oxidation reaction (MOR), compared to Pt/RGO, Pd/RGO, commercial Pt black and Pd black. (C) 2014 Elsevier Ltd. All rights reserved.