MWNTs have been synthesized by the pyrolysis of acetylene using hydrogen decrepitated Mischmetal (Mm)-based AB(3) alloy hydride catalyst using chemical vapor deposition (CCVD) technique. Nanocrystalline Pt dispersed multi-walled carbon nanotubes (Pt/MWNTs) have been prepared by chemical reduction method using functionalized MWNT. MWNT and Pt/MWNT have been characterized by SEM, TEM, HRTEM, Raman, TGA and XRD studies. Hydrogen storage properties of as-grown, purified and nanocrystalline Pt dispersed MWNT have been investigated using high-pressure Seiverts' apparatus in the pressure range of 1-100 bar and at 298 and 125 K. The effects of purification and dispersion of Pt nanoparticles on the hydrogen storage capacity have been discussed. (c) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.