The development of highly efficient CO2 capture materials would contribute to reducing atmospheric CO2 in air and avoiding irreversible climate change. Therefore, it is important to propose a useful evaluation system that allows for rapid screening of promising CO2 capture materials. In this study, we used a solid electrolyte CO2 sensor for the performance evaluation of CO2 capture materials in place of large and expensive analytical equipment. We examined the ability of polyethylenimine (PEI)-coated silica (SiO2-PEI), which can capture ppm (parts per million)-level CO2 in air at room temperature. The CO2 sensor clearly indicated that the CO2 concentration in the outlet gas decreased after a sample gas containing ppm-level CO2 in air passed through an adsorption column packed with SiO2-PEI. From the sensor signal, the CO2 adsorption capacity and rates of adsorption and desorption were successfully estimated. We also evaluated the CO2 capturing properties of CaO using our CO2 sensor. The results demonstrate that the use of the cheap, compact, and efficient CO2 sensor is feasible for the performance evaluation of CO2 capture materials. © 2020 Elsevier B.V.