it is just the best time to compile and compare the experimental data and to explore the possible laws and to discover the relation between the crystallographic parameters, thermodynamic and electrochemical properties, based on lot of the published experimental data about the hydrogen-storage alloys. An empirical correlation between the unit cell volume and the enthalpy change, equilibrium pressure, discharge capacity has been constructed. The violent change of the equilibrium pressure with the unit cell volume might indicate the change in the interaction nature between the host alloy atoms and the intercalated hydrogen atoms. The dependence of unit cell volume vs. average numbers of total electrons for AB(5)-type alloys exhibits same change tendency as that of the Vanderwaals radius vs. atomic numbers from Fe to Se in the elements' periodic table. it is possible that the total numbers of the electrons decides the unit cell volume. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All fights reserved.