A non-stoichiometric Zr-based alloy with the composition of Zr0.8Ti0.5V1.7 is designed to investigate the hydrogen absorption properties against gaseous impurities at different temperatures. The alloy has been synthesized by arc melting and annealing treatment. Microstructure, hydrogen absorption properties in presence of air impurities, hydrides and dehydrogenation behavior of the annealed Zr0.8Ti0.5V1.7 have been investigated in this work. The results reveal that 0.1 mol.% air impurities in hydrogen decrease the initial absorption rate but preserve no significant effect on the hydrogen storage capacity of the experimental alloy at 25 degrees C. 1 mol.% air impurities evidently deteriorate the hydrogen absorption ability of alloy at temperature below 180 degrees C and the poisoning effect declines with the increase of temperature. Gaseous impurities have little impact to the absorption behavior of fully activated alloy at temperature above 340 degrees C. The above results indicate that the poisoning effect of gaseous impurities on hydrogenation properties of alloy depends on the concentration and temperature, and the tolerance of alloy to gases poisoning can be improved after one saturated hydrogen absorption/desorption cycle. DSC curve reveals the multi-stage dehydrogenation behavior of alloy. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.