Binary MgH 2 –xwt% C mixtures (x=0, 2, 5 and 10wt% for carbon fibers (CFs), 10wt% for graphite (G) and diamond (D)) were prepared by hand mixing and by ball milling (5h) for MgH 2 –10wt% CFs. The aims of the work were: – to investigate the dehydriding reaction of MgH 2 catalyzed by carbon under microwave irradiation; – to assess the effect of presence of different carbon type and content on the desorption reaction; – to evaluate the influence microwave power on the rate of hydrogen release; to study the influence of milling process on the dehydrogenation time. The amount of hydride and Mg phases (e.g. hydrogen content) was estimated from XRD pattern matching (Eva and Fullprof). The morphology of the powders and the particle size distribution were observed by Scanning Electron Microscopy (SEM) and laser granulometry respectively. Carbon distribution in the MgH 2 matrix was investigated by electron probe microanalyses.The different carbon type transfer the heat, generated from absorbed microwave irradiation, to the MgH 2 matrix which induces the hydrogen release. It was found that the dehydrogenation rate and time were enhanced with rising carbon content, microwave power and with milling time. For the MgH 2 –10wt% CFs mixtures, under 1500W of microwave, more than 90% of conversion MgH 2 to Mg phases was obtained after 20s for hand mixing mixture and after only 10s for 5h ball milled one.