Effect of H2S impurity on hydrogen permeation of Pd60Cu40/V-15Ni composite membranes was investigated in the temperature range of 473-673 K in this paper. Hydrogen permeability of the composite membrane shows a good resistance to H2S impurity when temperature is between 573 and 673 K; however, when temperature is below 573 K, it decreases rapidly with increasing the H2S content; furthermore, hydrogen permeability of the composite membrane could recover when H2S impurity was eliminated. On the other hand, hydrogen diffusion measurement shows that hydrogen diffusion coefficient of the composite membrane is indifferent to H2S impurity in the temperature range of 473-673 K. The decrease of hydrogen solubility below 5(7)3 K, which results from the stronger adsorption of H,S molecules to the membrane surface in low temperature and the consequent reduction of effective H-2 adsorption sites, should be the main reason of the degradation of hydrogen permeability of the composite membrane by H2S impurity in low temperature. (C) 2007 Elsevier B.V. All rights reserved.