Ball milling of magnesium hydride with germanium additives in argon for up to 10 h was shown to result in the formation of nanocomposites of alpha- and gamma-modifications of MgH2 together with individual Ge phase. When the as milled samples are heated-up, Ge interacts with MgH2 to form Mg2Ge at T = 350-400 degrees C; the phase transformation overlaps with MgH2 decomposition and Mg2Ge phase remains in the material after its re-hydrogenation at T = 300 degrees C and P(H-2)similar to 15 bar. The ball milled Ge-MgH2 nanocomposites were found to be characterised by an improved hydrogen release via hydrolysis in organic acid solutions as compared to pure MgH 2 prepared and tested at the same conditions. It was found that the composite containing 5 wt% of Ge and ball milled for 5 h showed the best hydrogen generation performance, with total hydrogen release exceeding 1.55 NL/g (yield close to 100%) in one minute. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.