The microstructures and phase composition of the pseudobinary ZrTi0.2V1.8 alloy were examined by scan electron microscope (SEM) and X-ray diffraction (XRD). Before hydrogenation, the hypoeutectic structure accompanied with ZrV2 + (ZrV2 + Zr) spherical-like texture has been observed in ZrTi0.2V1.8 and the dominant phase could be ascribed to the C15 Laves phase. Hydrogen absorption pressure-composition isotherms (P-C isotherms) and hydriding kinetics of ZrTi0.2V1.8 were investigated by pressure reduction method using Sievert apparatus from 673 to 823 K. At hydrogen concentration 0.65 (H/A), the relative partial molar enthalpy and entropy calculated by Van't Hoff equation are -60 +/- 1 kJ mol(-1) and -119 +/- 1 J mol(-1) K-1, respectively. In addition, two stages in the hydrogen absorption reaction between 673 and 823 K could be attributed to the different hydrogen absorption mechanisms including redistribution of the hydrogen atoms in the hydride phase and the diffusion of hydrogen in the (beta-phase. The activation energy E-a of the alloy is similar to 3.6 kJ mol(-1) for the first absorption stage and -61.9 kJ mol(-1) for the second one. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.