The present study deals with investigations on the AB 5 -type MmNi 4 . 6 Fe 0 . 4 hydrogen storage alloy with improved storage capacity of ~1.7wt%. The as-synthesized MmNi 4 . 6 Fe 0 . 4 intermetallic alloy has a storage capacity of ~1.5wt% with kinetics ~25cm 3 /min/g. In search of effects, which may lead to improvement of storage capacity and kinetics, we have carried out several possible material modifications including substitution of 3d-transition elements such as Fe, Co, Mn, etc. at Ni sites, surface treatment and ball-milling. It has been found that the last material modification, i.e. ball-milling technique gives optimum results. The ball-milling technique parameters like speed, time duration, ball to powder ratio and medium of milling has been optimized. The maximum storage capacity of ~1.7wt% with kinetics of ~35cm 3 /min/g is obtained when pulverization of the as-synthesized (RF melted) material employing an attritor mill. By varying the medium, duration and speed of ball milling, it was found that the optimum conditions and estimates correspond to medium: hexane, duration: 10 min, speed: 200 rpm. The PCT evaluation was carried out using Sievert's type apparatus. The structural and microstructural characterizations were explored using XRD and SEM. XRD explorations revealed that full-width at half-maximum (FWHM) before and after pulverizations are 0.20 and 0.25 o , i.e. there is a broadening of ~25% in the width of the peaks after pulverization. The microstructural investigations revealed that the average particle size of MmNi 4 . 6 Fe 0 . 4 after pulverization was ~2.5 times less than that of the as-synthesized alloy. Smaller particles together with fresh surfaces are the most likely cause of enhanced hydrogenation (storage capacity and kinetics) behaviour.