Abstract The hydrides of Ce 0.7Nd 0.3Ni 2.5Cu 2.5 and the CeNi 5− x− y Cu x Al y quaternaries with 2 < x < 2.5, 0.2 < y < 0.5 and 2.5 < x+ y < 3.0 were prepared and studied as a function of composition, temperature (0–120°C) and hydrogen pressure (0.01–50 atm). The binary CeNi 5, which is not a hydrogen absorber, becomes an excellent hydrogen storage material in the presence of neodymium, copper and aluminum. The hydrogen densities of these quaternary alloys relative to liquid hydrogen are in the range 0.9–1.2. Both copper and aluminum reduce the vapor pressure of the hydride, but the latter has a more dramatic effect. The kinetics of hydrogen sorption are extremely rapid. The enthalpy and entropy of dehydrogenation are in the range 14.2–26.5 kJ (mol H 2) −1 and 49–70 J mol −1 K −1 respectively. The excellent physicochemical properties and the lower cost of the CeNi 5− x− y Cu x Al y quaternaries make them quite attractive for a variety of engineering applications.