We report the synthesis and spectro-electrochemical characterization of platinum black and carbon-supported platinum with varying amounts of carbon support for fuel cell applications. The Structural aspects of the carbon-supported Pt-catalysts were Studied using XRD, HRTEM and XPS. The broad XRD peaks indicated the presence of nanoparticles of Pt, which was well complemented by the HRTEM studies. The valence states and the variation of the binding energy with respect to the particle size of the electrocatalysts were elucidated by XPS studies. The metal-support interaction in these carbon-platinum electrocatalysts and their influence on the oxidation of CO and methanol are also reported. The nanosturucture nature of the catalysts and its influence on the methanol oxidation are related and discussed. (C) 2004 Elsevier B.V. All rights reserved.