Amorphous-crystalline composite ribbons of quaternary Mg-Ni-(Y,La)-Pd alloys are produced via rapidly solidification and used as precursors for creating nanocrystalline hydrogen storage materials. The resulting materials demonstrate relatively high hydrogen capacity of around 4.5 mass% H and excellent absorption/desorption kinetics at 573 K. Additionally, the alloys demonstrate reversible hydrogen storage at 473 K. A composition of Mg85Ni10Y2.5Pd2.5 fully absorbs and desorbs 4.6 mass% H in 90 min. The cyclability of the quaternary alloys demonstrates good stability, with little loss in maximum capacity through 8-10 cycles. This has been attributed to the improved stability of the nanocrystalline structure attained via the Y and La additions. Thermodynamically, the enthalpy of the hydrogen absorption reaction is reduced by 5 kJ/mol in the quaternary alloys, compared to Mg-MgH2; while the entropy of reaction is also reduced. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.