The PtxSn/C (x=1,2,2.5,3,4) anodic catalysts for direct ethanol fuel cell (DEFC) have been prepared by an improved microemulsion method. Ethylene glycol is used as cosurfactant, and metal precursors, are dissolved in it beforehand to prevent the hydrolysis of metal precursors. The composition, particle size and structure of these catalysts are characterized by energy dispersive X-ray spectrum (EDX), transmission electron microscope (TEM) and x-ray diffraction (XRD). The results show that the synthesized Pt3Sn/C catalyst has part of Pt and Sn alloying. The average diameter is about 2.9nm, and has a narrow size distribution and a good dispersivity. The electrochemical experiments indicate that the Pt3Sn/C catalyst prepared in the neutral microemulsion has superior catalytic activity for ethanol oxidation. The PtxSn/C nanoparticle formation in the improved microemulsion is also discussed. (C) 2010 Elsevier B.V. All rights reserved.