Electrochemical hydrogenation of benzene to cyclohexane was studied over carbon-supported Pt and Pt-based alloy catalysts (e.g., Pt/C, Pt4Rh1/C, Pt4Rh0.75W0.25/C, Pt4Rh0.75Mo0.25/C, and Pt4Rh0.75Pd0.25/C),, which were prepared using a borohydride reduction method combined with a freeze-drying procedure. The Pt4Rh0.75W0.25/C catalyst showed the best performance for the electrochemical hydrogenation of benzene to cyclohexane over a proton exchange membrane fuel cell (PEMFC) system. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate structural modifications on the Pt-based catalysts. in which the carbon-supported Pt-based binary and ternary catalysts indicated effective alloy formation with decreased lattice parameters as compared to Pt/C. X-ray photoelectron spectroscopy (XPS) and X-ray absorption-near-edge spectroscopy (XANES) were also carried out to characterize electronic features of the Pt-based alloy catalysts, in which both the structural and electronic modifications were closely associated with the benzene hydrogenation activities. (C) 2009 Elsevier B.V. All rights reserved.