Nanocrystalline and amorphous NdMg12-type NdMg11Ni + x wt% Ni (x = 100, 200) hydrogen storage alloys were synthesized by mechanical milling. The effects of Ni content and milling time on hydrogen storage thermodynamics and dynamics of the alloys were systematically investigated. The gaseous hydrogen absorption and desorption properties were investigated by Sieverts apparatus and differential scanning calorimeter connected with a H2 detector. Results show that increasing Ni content significantly improves hydrogen absorption and desorption kinetics of the alloys. Furthermore, varying milling time has an obvious effect on the hydrogen storage properties of the alloys. Hydrogen absorption saturation ratio (