The Li-Mg-N-H system consists of lightweight materials with high hydrogen capacity and thus it is of interest for hydrogen storage application. In this work, different amount of LiNH2 in the Li3N-MgH2 (1:1) system was added to enhance the hydrogen storage properties. The mixtures of LiMgN, LiH and LiNH2 were obtained after ball milling of Li3N -MgH2-xLiNH(2) (x = 0, 0.13, 1 and 2 mol). The addition of LiNH2 results in the microstructural change of dispersion of the particles with the refined grains, shortening of the diffusion distance of hydrogen. The hydrogen absorption/desorption capacities of all samples were greatly improved by the addition of LiNH2. The hydrogen storage capacity was improved from 3.2 wt% to approximately 5.1 wt% at 250 degrees C by the addition of LiNH2 from 0 to 2 mol. The microstructural evolution and hydrogen storage mechanisms during the hydrogenation/dehydrogenation process for the Li3N-MgH2-2LiNH(2) sample are discussed. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.