A char was made from walnut shell which was gasified in CO₂ atmosphere and its physical properties such as pore size distribution, density, pore volume and surface area were measured. The effects of reaction temperature and conversion（X_c） on the pore structure change of char were examined and compared with the theoretical values from the mathematical models (pore volume model and random pore model). The char which has bimodal pore distribution near by 10 Å(micro pore) and 10⁴ Å(macro pore) was obtained by CO₂ gasification reaction. At lower reaction temperatures the surface area(㎡/g-s.m.) and the micro pore volume (㎤/g-s.m.) were increased but the macro pore volume was not affected by the reaction temperatures. It was found that the random pore model was agreed with the pore structure data which were obtained from gasification of the char.