Composite membranes based on Ni and Zr-doped BaCeO 3 are promising for hydrogen separation. Such composites show high proton conductivity and adequate chemical stability in H 2 O and CO 2 , but may be unstable in H 2 S. In this work, the hydrogen permeation performance of Ni–BaZr 0.1 Ce 0.7 Y 0.2 O 3−δ was measured in an H 2 S-containing atmosphere at 900°C. The hydrogen permeation flux began to degrade in 60ppm H 2 S and decreased by about 45% in 300ppm H 2 S. After hydrogen permeation tests, X-ray diffraction analysis revealed the formation of BaS, doped CeO 2 , Ni 3 S 2 and Ce 2 O 2 S. Analysis of the microstructure and phase composition, and results of thermodynamic calculations suggest that reaction between H 2 S and doped BaCeO 3 caused the performance loss of the Ni–BaZr 0.1 Ce 0.7 Y 0.2 O 3−δ .