Composite powders of CeO2 and CaO (Ce/Ca composite) with CeO2/CaO weight ratios of 0, 0.5, 1, and 2 were synthesized by heating precipitates consisting of CaC2O4 and CeO2 at 900 degrees C under Ar gas flow. X-ray diffractometry (XRD) and reflected electron imaging clarified that the Ce/Ca composites consisted of CeO2 and CaO phases and the CeO2 particles were well dispersed in the CaO powders. XRD and X-ray photoelectron spectroscopy revealed that the carbonation of CaO and the production of Ce3+ in CeO2 of the Ce/Ca composite were promoted with increasing temperature under CO2 gas flow. The activation energy of the carbonation decreased from approximately 107 to 40 kJ mol(-1) with increasing CeO2/CaO weight ratio from 0 to 2. (C) 2017 Elsevier B.V. All rights reserved.