The present work is focussed on the synthesis, structural/microstructural characterization, hydrogenation behaviour and computer simulation studies of P-C isotherms of a new series of alloys represented by La(x)Mm(1-x)Ni(5-y)Fe(y) (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 and y = 0. 1), where Mm denotes Ce-rich mischmetal. The alloys have been analysed using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. The alloy corresponding to LaNi4.9Fe0.1. I has been found to have high storage capacity of similar to 1.68wt% which is one of the highest reported capacity for AB(5) type storage systems. A feasible mathematical model has been developed to simulate the P-C isotherms. The model describes the asymmetry of the 'pressure-composition' isotherms, temperature-dependent plateau slopes and smooth transitions between alpha, alpha+beta and beta-regions. P-C isotherms, enthalpy and entropy changes (Delta H and Delta S) have been evaluated experimentally for the alloys La(x)Mm(1-x)Ni(4.9)Fe(0.1) in order to have input data for the simulation. Special software was developed to simulate the P-C isotherms using the said model. The simulated and experimental curves have been found to match closely. (c) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.