Pt nanoparticles have been supported on different carbon materials for their use as electrocatalysts in polymeric electrolyte fuel cells. Carbon nanofibers (CNF) and ordered mesoporous carbon (CMK-3) have been studied as supports that could replace carbon black in the preparation of commercial electrocatalysts. The use of these non-conventional carbon materials allowed the determination of the influence of the support on the physicochemical properties of catalysts. Additionally. Pt catalyst supported on Vulcan XC-72R (commercial electrocatalyst support) has been prepared in order to establish a comparison. Catalysts were prepared by the incipient wetness impregnation method, and subsequently, they were reduced in a H-2 flow. Supports and catalysts were characterized by different analytical techniques in order to determine the effect of the support. Results proved that the support has a strong influence on the physicochemical properties of catalysts. These properties depended on the nature of the support and are associated with the metal support interaction. (C) 2011 Elsevier B.V. All rights reserved.