Electrochemical conversion reaction of MgH2 with Li ion enables the production of in-situ nanometric Mg and MgH2 particles so-called (nano-Mg) (INSITU) and [(nano-MgH2)(INSITU)] showing interesting hydrogen sorption properties with hydrogen absorption at 100 degrees C under 10 bars of hydrogen pressure (PH2) and desorption at 200 degrees C under primary vacuum, respectively. Differential Scanning Calorimetry (DSC) measurements of MgH2 electrochemically prepared confirmed a decrease in the desorption temperature from 416 degrees C to 295 degrees C and in the heat of formation from -74 kJ mole mol(-1) (H-2)(-1) to -56 kJ mol(-1) (H-2)(-1) for commercial (particle size diameter: 10 mu m-100 gm) and as prepared MgH2 hydride (particle size: 10 nm-40 nm), respectively. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.