Artificial graphite generally manufactured by carbonization sintering of shape-body of Kneaded mixture using granular cokes as filler and pitch as binder, going through pitch impregnation process if necessary and finally applying graphitization heat treatment. The effect of thermal oxidation with air or CO2 atmosphere on IG-11 graphite samples was investigated. The results show a localized oxidation process which progressively reveals the large coke particles with increasing overall weight loss in air. The surface of graphite was peel off which was not changed the specific gravity after air oxidation. However, the specific gravity of graphite continuously decreased by CO2 oxidation. Decreasing of specific gravity in the CO2 oxidation was because that CO2 gas ingress the surface to interior. The pore shape after the CO2 oxidation showed the longneck beakers.