Commercial MgH2 powder was mechanically (ball) milled without and with nanosized Cr2O3 particles in different types of ball mills using various milling conditions. The results demonstrate that the high-energy ball milling greatly improves the hydrogen absorption/ desorption kinetics of MgH2. There is no significant difference in the sorption properties between powders milled in different commonly used mills. It was noticed that samples ball-milled in a planetary ball mill show improved desorption kinetics. in this study very favorable effect of Cr2O3 nanoparticles on hydrogen sorption kinetics was observed. The crystallite size of beta-MgH2 after milling without or with nano-Cr2O3 is almost the same (similar to 10nm). In contrast to that, the specific surface area of MgH2 powder after milling with nanosized Cr2O3 decreases significantly as compared to the powder milled without catalyst. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.