Adsorption kinetics of CO2 gas on Zeolite 13X at high temperature and pressure (similar to 600 K, similar to 1 MPa) has been investigated experimentally and numerically for application to a CO2 storage system in a CaO/CaCO3 type high-temperature chemical heat pump (CHP). The analytical model adopted reasonably simulates the empirical adsorption profiles on the assumption that mass transfer is controlled by pore diffusion and heat involved by adsorption is transferred within the particle by conduction. The adsorption of CO2 on Zeolite 13X proceeds very fast under the present conditions, and the rate of adsorption was verified to be sufficient to store the CO2 gas produced by decomposition of CaCO3 in the proposed CHP. However, since the adsorption in the early stage is greatly hindered by the heat of adsorption, removing the heat involved by adsorption is very important for the practical use.