In this paper, the cyclic stabilities and the mechanism of capacity decay of (La0.65Ca0.35) (Mg1.32Ca0.68)Ni-9 AB(3)-type alloys were specifically clarified, which have seldom been studied previously. The results indicated that AB(3) phase in the La-Mg-Ca-Ni AB(3)-type alloys decomposed after repeated hydrogen sorption cycles, due to the serious mismatch of AB(2) and AB(5) subunits. In addition, we evidently found that the formation of MgNi2 owing to the decomposition of AB(3) phase was mainly responsible for the capacity decay, which might shed light on the further investigation of AB(3)-type alloys. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.