Syngas has been produced from carbon dioxide (CO2) and steam using a proton ceramic electrolyser cell. Proton-conducting electrolytes which exhibit high conductivity can suffer from low chemical stability. In this study, to optimize both proton conductivity and chemical stability, barium cerate and doped barium cerate are synthesized using solid state reaction method: BaCeO3 (BC), Ba0.6Sr0.4CeO3-alpha (BSC), Ba0.6Sr0.4Ce0.9Y0.1O3-alpha (BSCY), and BaCe0.6Zr0.4O3-alpha (BCZ). The BC, BSC, and BSCY are calcined at 1100 degrees C for 2 h and BCZ is calcined at 1300 degrees C for 12 h, respectively. All samples exhibit 100% perovskite and crystallite sizes equal 37.05, 28.46, 23.65 and 17.46 nm for BC, BSC, BSCY and BCZ, respectively. Proton conductivity during steam electrolysis as well as catalytic activity toward the reverse water gas shift reaction (RWGS) is tested between 400 and 800 degrees C. The conductivity increases with temperature and the values of activation energy of conduction are 64.69, 100.80, 103.78 and 108.12 kJ mol(-1)( )for BSCY, BC, BSC, and BCZ, respectively. It is found that although BCZ exhibits relatively low conductivity, the material provides the highest CO yield at 550-800 degrees C, followed by BSCY, BSC, and BC, correlating to the crystallite size and BET surface area of the samples. Catalytic activity toward RWGS of composited Cu and electrolytes is also measured. Additional Cu (60 wt%) significantly increases catalytic activity. The CO yield increases from 3.01% (BCZ) to 43.60% (Cu/BCZ) at 600 degrees C and CO can be produced at temperature below 400 degrees C. There is no impurity phase detected in BCZ sample after exposure to CO2-containing gas mixture (600 degrees C for 5 h) while CeO2 phase is detected in BSC and BSCY and both CeO2 and BaO are observed in BC sample. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.