Ni-BaZr0.1Ce0.7Y0.1Yb0.1O3-delta (Ni-BZCYYb) membrane shows improved and stable performance in dry H-2 and CO2 (Fang et al., ACS Appl. Mater. Interfaces 6 (2014) 725-730). However, the stream from steam methane reforming contains high contents of H2O, CO2, and CO, which poses crueler challenges to the chemical stability of Ni-BZCYYb membrane than dry H-2 and CO2. In this work, we tested the Ni-BZCYYb membrane in wet H-2 and CO2 which generated high content of H2O and CO due to reverse water gas shift (RWGS) reaction at high temperature. High content of H2O improves the proton conductivity of BZCYYb and hydrogen transport through the membrane. On the other hand, H-2 content reduction and decomposition of BZCYYb promoted by high content of H2O lead to performance degradation. The steady-state hydrogen flux may increase or decrease depending on the balance among these effects. Besides, CO-induced Ni corrosion was found in both surface and bulk due to metal dusting. In general, Ni-BZCYYb membrane still displayed much better performance stability in wet H-2 and CO2 than Ni-BaCe0.8Y0.2O3-delta and Ni-BaZr0.1Ce0.7Y0.2O3-delta composites, making it a candidate material system for further studies aimed at membrane processing of hydrocarbons. (C) 2014 Elsevier B.V. All rights reserved.