Homogeneously annealed Zr0.9Ti0.1V2 samples are firstly exposed to contamination gases of O-2 and N-2 for 30, 60 and 180s at the ambient temperature, respectively. Hydrogen absorption properties are examined after poisoning and regeneration. The compositions and valence in the surface and sub-surface are investigated by X-ray photoelectron spectroscopy (XPS). The hydrogen absorption capacity of the alloy has been almost entirely degraded by the oxygen poisoning. After the regeneration, the oxygen-poisoned sample can hardly absorb hydrogen while the nitrogen-poisoned sample re-obtains the hydrogen absorption capacity with the value as 2.85 H A(-1) (molar ratio of hydrogen to alloy). The activation temperature of the oxygen-poisoned sample is similar to 100 K higher than the value of the unpoisoned one. With the help of ion etching, it is found the thickness of the passivated surface layer of the oxygen-poisoned sample was similar to 58 nm. However, the thickness of the passivated surface layer of the un-poisoned sample is only similar to 36 nm. That is the reason why the oxygen-poisoned sample cannot renew the hydrogen absorption capacity under the same regeneration conditions as in the un-poisoned one. (C) 2011 Elsevier B.V. All rights reserved.