A sample with a composition of 84wt% MgH2–10wt% Ni–2wt% NaAlH4–2wt% Ti–2wt% CNT (named MgH2–10Ni–2NaAlH4–2Ti–2CNT) was prepared by milling in a planetary ball mill under H2. Activation of the sample was not required. At the first cycle, the sample absorbed 3.75wt% H for 10min, and 4.17wt% H for 60min at 593K under 12bar H2. Reactive mechanical grinding of Mg with Ni, NaAlH4, Ti, and CNT is thought to create defects on the surface and in the interior of Mg, as well as to reduce Mg particle size.