Iron-modified carbon-supported platinum electrocatalysts were synthesized by the Bonnemann colloidal method. Physical characterization by the methods of Brunauer-Emmett-Teller, transmission electron microscopy, and X-ray diffraction measurements were conducted to explore the catalyst surface area and particle size, particle distribution, degree of metal alloy, and phase structure. Electrochemical measurements were carried out to characterize the catalyst oxygen reduction reaction (ORR) activity under the condition of with and without methanol present. The catalyst performance was evaluated by rotating disk electrode sweep voltammetry and cyclic voltammetry techniques. The PtFe catalysts showed enhanced methanol tolerance and catalytic activity compared to Pt catalyst. The PtFe catalysts with atomic compositions of Pt/Fe=9:1 and Pt/Fe=1:1 showed more enhanced methanol tolerance and catalytic activity than the Pt/Fe=3:1. (c) 2007 The Electrochemical Society.