Pt-Sn-Ni/C and the Pt-Sn/C supported catalysts with potential application in a direct ethanol fuel cell (DEFC) were prepared by a chemical reduction method. The Vulcan XC-72R (Vu) used as carbon support was chemically treated with concentrated HNO(3) (Vu(t)) and then analyzed by thermal programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). The catalyst particles were characterized by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements were performed by using a glassy carbon working electrode covered with the catalyst powder in a 1M ethanol + 0.5M H(2)SO(4) solution at 60 degrees C. EIS shows that ethanol oxidation (EO) on the Pt-Sn-Ni/Vu(t) catalyst at various potentials exhibits different impedance behaviors. The catalytic activity of the Pt-Sn-Ni/Vu(t) catalyst for EO is higher than that of the Pt-Sn/Vu(t) catalyst. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.