Mesoporous PtSn, PtSnRu and PtSnOs catalysts were prepared by chemical co-reduction of metal salts in a building block of the liquid crystalline phase of a nonionic surfactant. XRD analysis revealed that the mean crystallite size of the prepared PtSn sample was approximately 4.3 nm with a high active surface area of 51 m(2) g(-1). The introduction of Ru and Os into the PtSn sample noticeably reduced their crystallite sizes. The third metal added could enhance tin deposition and this tin acted as a barrier preventing Pt agglomeration during catalyst synthesis. The results from electrochemical evaluation revealed that the addition of the third metal (Ru and Os) to PtSn lowered the onset potential and increased the current of ethanol oxidation at both reaction temperatures of 20 degrees C and 60 degrees C. Among these three catalysts, PtSnOs showed higher activity for ethanol oxidation due to the enhancement of CO oxidation by the more oxophilic property of Os. (C) 2012 Elsevier B.V. All rights reserved.