To improve hydrogen desorption properties of MgH2, mechanical milling of MgH2 with low concentration (2 and 5%) of NaNH2 has been performed. Pre-milling of MgH2 for 10 h has been done and then six samples have been synthesised with different milling times from 15 to 60 min. Microstructural characterisation has been performed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser scattering measurements (PSD), and correlated to desorption properties examined using Differential Scanning Calorimetry (DSC) and Hydrogen Sorption Analyser (HSA). Thermal analysis shows that desorption temperatures are shifted towards lower values. It also highlights the significance of milling time and additive concentration on desorption behaviour. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.