The plate-like CaO particle with a highly (111)-plane orientation was synthesized, and its CO2 adsorption property was investigated. Firstly, the Ca(OH)(2) powders were prepared from a saturated Ca(OH)(2) aqueous solution, and then the prepared Ca(OH)(2) powder was thermally decomposed to synthesize the CaO powder. The orientation degree of the (0001) plane of Ca(OH)(2) was increased by increasing the time for evaporating the solvent in the Ca(OH)(2) aqueous solution. The orientation degree of the (111) plane of CaO increased by increasing that of the (0001) plane of Ca(OH)(2). Increasing the orientation degree of the (111) plane of CaO was effective for suppressing the aggregation of CaO particles in the CaO powder. Consequently, it was found that the CO2 adsorption rate was increased by increasing the specific surface area of the CaO powder. Furthermore, the (111) plane-oriented CaO powder maintained the CO2 adsorption ratio even after the cycle of CO2 adsorption and desorption at 700 degrees C. (C) 2017 Published by Elsevier B.V.