We have studied systematically the effects of synthesis parameters in both precipitation and colloidal methods to obtain highly dispersed Pt/carbon catalyst and compared the characteristics of prepared catalysts with commercial ones. The average Pt particle size at optimum condition for 10-60 wt.% Pt/carbon was in the range 1.7-3.8 nm which was about 70-80% of the commercial catalysts at the same Pt loading. The Pt surface area was also 20-40% higher than those of the commercial catalysts. The activities of prepared catalysts, measured by a single cell unit, were comparable with those of commercial ones. (C) 2003 Elsevier B.V. All rights reserved.