The destabilizing effect of (X) group IV elements (C, Si, Sn and Ge) on NaH + Al was investigated. A significant decrease in the desorption temperature as well as the reaction enthalpy of NaH was achieved with additions of C. Si, Ge and Sn due to the formation of NaAlGe and NaAlSi ternary and NaSn binary compounds. Compared to a reaction enthalpy of 114 kJ mol(-1) H-2 for NaH above 400 degrees C, lower reaction enthalpies of 94 kJ mol(-1) H2, 72 kJ mol(-1) H-2, 20 kJ Mol(-1) H-2 and 2 kJ mol(-1) H-2 were obtained for the NaH + Al + C, NaH + Al + Si, NaH + Al + Ge and NaH + Al + Sn mixtures with onsets at 270 degrees C, 220 degrees C, 180 degrees C, and 130 degrees C respectively. Reversible hydrogenation was partly achieved in the NaH Al Si system with the formation of NaAIH(4) + Si. (C) 2011 Elsevier Ltd. All rights reserved.