The hydriding characteristics of Zr-based AB(2) alloy produced by gas atomization have been investigated during its absorption-desorption reaction with hydrogen gas its gas-phase hydrogenation properties are different from those of specimens prepared by conventional methods. For the particle morphology of the as-cast and gas-atomized powders, it can be seen that the mechanically crushed powders are irregular, while the atomized powder particles are spherical. In PCT (Pressure-Composition-Temperature) measurements, for the gas-atomized particles smaller than 50 mu m, the hydrogen storage capacity is dramatically decreased and the hysteresis loop becomes larger than that of the gas-atomized particles larger than 50 mu m. In addition, the increase of jet pressure of gas atomization. results in the decrease of hydrogen storage capacity and the slope of plateau pressure significantly increases. TEM and EDS studies showed the increase of jet pressure ill the atomization process accelerated the phase separation within grain of the gas-atomized alloy, which brought about a poor hydrogenation property. In the measurements of hydrogen absorption-desorption kinetics, the improvement of desorption kinetics of gas-atomized AB(2) alloys was mainly caused by the higher plateau pressure, which is attributed to the smaller grain size and higher site energy for hydrogen in the gas-atomized alloys (C) 2009 Professor T. Nejat Veziroglu Published by Elsevier Ltd. All rights reserved.