1H and H 2 NMR spectra have been measured for amorphous MgNi-H(D) and nanostructured Mg 2 Ni-D systems synthesized by reactive mechanical grinding. H 1 MAS NMR spectra indicate that the dominant phase in the amorphous MgNi-H system is an amorphous MgNi-H phase and that a small amount of an amorphous/disordered α-MgH x phase is contained. Hydrogens are randomly distributed in the amorphous MgNi-H phase. H 2 NMR spectra demonstrate that hydrogen motion is faster in the order of the nanostructured Mg 2 Ni-H, the crystalline Mg 2 NiH 4 and the amorphous MgNi-H systems.