For gaining further insight into the involvement of the gaseous and electrochemical hydrogen storage properties of CeMg12-type alloys, partial substitution and ball milling were both used to synthesize the nanocrystalline and amorphous CeMg11Ni + x wt.% Ni (x = 100, 200) samples. This research aims at elucidating the functional roles of Ni content and milling time on samples' structure and hydrogen storage performance. X-Ray diffraction and high-resolution transmission electron microscope were used to reveal the micro constructions of alloys. To determine the gaseous hydrogen storage property, Sievert's apparatus and a thermal gravity analysis bonded with a H-2 probe were adopted. The dehydrogenation activation energy was computed in the Kissinger method. The electrochemical performances of the as-milled samples were measured through a constant current system. Further researches showed that the electrochemical performance of as-milled samples had been dramatically improved by increasing Ni content. With milling duration lengthens, the gaseous hydrogen absorption capacity, gaseous hydriding rate and high rate discharge capability of samples reached the maximal values, but electrochemical discharge capacity and gaseous dehydriding rate always increased. The dehydrogenation activation energy decrease resulted by improving Ni percent and milling duration was deemed as the cause of the excellent gaseous kinetics of samples. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.