A Li-Mg-N-H system is a highly promising source of hydrogen storage materials due to its favorable thermodynamics and potential reversibility. Its application has been greatly hindered, however, by its rather high activation energy barriers. Herein, we report a novel multi-reaction methodology for the synthesis of nanosized Li2Mg(NH)(2) space-confined into thin-film hollow carbon spheres (THCSs) with a uniform dispersion. It shows that a completely depressed release of ammonia and reversible hydrogen sorption at a temperature of 105 degrees C, the lowest temperature reported so far, were achieved for the nanoconfined Li2Mg(NH)(2). Furthermore, a stable cycling capacity close to the theoretical value was also successfully realized, even through up to 20 cycles of de-/re-hydrogenation.