Nevertheless, the estimated values of the activation energy of hydrogen generation by hydrolysis of MgH2 in 1 wt.% solutions of organic acids were found to be significantly lower than the reported value for MgH2 hydrolysis in de-ionized water (~58 kJ/mol) and close to the value of ~30 kJ/mol determined for the hydrolysis in 4.5 wt.% solution of NH4Cl . The activation energy for 1 wt.% solution of citric acid estimated with a reasonable accuracy (20±4 kJ/mol) was found to be significantly lower. It can be seen from Figure (left) that the nanostructured MgH2 prepared by ball milling of Mg in H2 is characterised by better hydrolysis performance than commercial magnesium hydride. Even in pure water, after 10 minutes from starting the process, the hydrogen yield for the ball milled MgH2 (10%) exceeds the H2 yield for the commercial MgH2 (3%) in more than 3 times. Addition of GLM and Ni/GLM to the ball milled MgH2 results in further increase of hydrogen yield during hydrolysis in deionised water to 20-25%. Ball milling of Mg in H2 with and without GLM and Ni/GLM additives also results in significant improvement of the reaction kinetics in 0.1M solution of the citric acid (Figure (left)): the hydrogen yield after 1 minute from starting the process increases from 30% for commercial MgH2 to 50% for ball milled MgH2 and, further, to 65% for the MgH2-GLM and MgH2-Ni/GLM composites.