Platinum and palladium nano-particles supported by graphitic nano-fibers (GNFs) have been prepared and used as cathodic electrocatalysts in proton-exchange membrane (PEM) water electrolysis cells for the hydrogen evolution reaction (HER). Raw GNF structures have been synthesized by chemical vapor deposition (CVD). Noble metal nano-particles have been deposited at the surface of GNFs using an impregnation-reduction method. Structural properties and electrochemical performances of the GNF-supported catalysts have been determined using TEM analysis and cyclic voltammetry. Current-voltage polarization curves have also been recorded using a PEM cell (7 cm(2)). The performances obtained with GNF-supported catalysts were found more efficient than those obtained with catalysts supported with conventional carbon black (Vulcan (R) XC-72). In particular, a reduced electrolysis cell voltage (1.67 instead 1.72 V at 1 A.cm(-2) and 90 degrees C) has been obtained using Pt/GNF cathodes in place of Pt/XC-72 at the cathode and with similar platinum contents (40 wt.%). Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.