We have investigated the ball-milling (5-45 h) followed by dehydrogenation kinetics of LiNH(2)-MgH(2) mixture. A new result of ball-milling reveals the formation of Mg(NH(2))(2) for mixtures ball-milled for more than 15 h. The desorption kinetics has been found to improve appreciably by increasing the duration of milling from 5 to 45 h. This enhancement is attributed to formation of Mg(NH(2))(2) during this process. It was found that the Mg(NH(2))(2) form through the reaction 2LiNH(2) + MgH(2) -> Mg(NH(2))(2) + 2LiH. The phase and microstructural characterizations have been done through X-ray diffraction, IR-spectrometry, transmission and scanning electron microscopy. Correlation between particle size and hydrogenation behavior has also been investigated. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.