To pursue high loading Pt/C with high dispersion, different types of carbon supports were used to prepare the Pt/C catalyst. The specific areas of the catalysts were characterized according to transmission electron microscopy and cyclic voltammetry methods. Carbon modified by impregnating normal nonane on high surface area carbon can give high dispersion for high loading Pt/C, i.e., the dispersion of 50 wt % Pt/C prepared with the modified carbon can be matched with the 20 wt % Pt/C. A high surface area of the carbon support is important in acquiring a high dispersion for high loading Pt/C, and the pore structure may also be influential to the catalyst dispersion because the micropores may cause loss of the catalyst dispersion. (C) 2003 The Electrochemical Society.