High dispersion of platinum nanoparticles on porous carbons has been synthesized from the composites of Pt complex salts, surfactants and a resorcinol/formaldehyde (RF) resin. A novel strategy of this method is to utilize electrostatic interactions between Pt complex ions and surfactants as well as RF resins and surfactants. The carbons prepared with the surfactant have high BET surface area and large micropore volume because of gas generation from surfactant molecules interacted with an RF polymer chain. The product has well-dispersed small Pt particles with a diameter of 2 nm. Surfactant molecules must interact not only with RF polymer but also with Pt complex ions to inhibit an aggregation of Pt particles. The Pt/carbon composite shows high catalytic activity for the oxidation of CO in H-2 rich feed gas. (c) 2005 Elsevier B.V. All rights reserved.