The effect of neodymium content on the structure and low-temperature (233 K) electrochemical properties of the La0.8-xNdxMg0.2Ni3.1Co0.25Al0.15 (x = 0.0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys was investigated systematically. The result of the Rietveld analyses suggested that all these alloys mainly consist of two phases: the (La, Mg)(2)Ni-7 phase and the LaNi5 phase. The electrochemical studies revealed that, at temperature 233 K, the maximum discharge capacity first increased from 188.5 mAh/g (x = 0.0) to 201.7 mAh/g (x = 0.1) and then decreased to 153.9 mAh/g (x = 0.4). The low-temperature dischargeability (LTD) first increased and then decreased with increasing x, also reaching an extreme when x was 0.10. The LTD was in agreement with the I-0, but was irrespective of the diffusion of hydrogen. From our work, the optimum composition of the La0.8-xNdxMg0.2Ni3.1Co0.25Al0.15 is (x = 0.0-0.4) alloy electrodes was found to be x = 0.10. (C) 2008 Published by Elsevier Ltd on behalf of International Association for Hydrogen Energy.