Pt-W nanoalloys with compositions ranging from Pt3W to PtW2 were explored as electrocatalysts for hydrogen oxidation reaction (HOR). It is shown that alloying Pt with W can lead to significantly enhanced electrocatalytic activity for HOR, with nearly 4 times increase in the exchange current density as compared with pure Pt. What's more, these Pt-W alloys possess superior CO tolerance to Pt and PtRu, mainly due to the weakened bonding of CO on their Pt-enriched surfaces. (C) 2012 Elsevier Ltd. All rights reserved.