The synthesis of polyaniline/platinum composites (PANI/Pt) has been achieved using both chemical and electrochemical methods. The direct chemical synthesis of PANI/Pt proceeds through the oxidation of aniline by PtCl62- in the absence of a secondary oxidant. SEM images of these samples indicate that the Pt particles are on the order of similar to 1 mu m for the chemically prepared composite. Electrochemical PANI/Pt synthesis is initiated by the uptake and reduction of PtCl62- into an a priori electrochemically deposited PANI film. This method produces a uniform dispersion of Pt particles with smaller particles with diameters ranging between 200 nm and 1 mu m. The results indicate that electrochemical methods may be more suitable for controlling particle dimension. Both materials show reduced proton doping relative to PANI without Pt, indicating the metal particles directly influence proton doping and the oxidation state of the polymer. The electrochemical data indicate that the conductivity in solution is sufficient such that the normal acid doping is attainable for PANI/Pt produced using either synthetic method. (c) 2005 Elsevier Ltd. All rights reserved.