An intrinsic mathematical model is developed for the investigation of the gas-solid reaction kinetics of high-purity graphite and oxygen. This model is based upon the oxygen transfer mechanism and uses physically meaningful parameters that are directly comparable to the experimental and theoretical literature of the carbon-oxygen reaction system. The model was used to extract reaction parameters for NBG-18 polycrystalline graphite for oxygen/nitrogen mixtures with a total pressure of 100 kPa. Experimental temperatures ranged from 500 to 850°C for oxygen partial pressures of 1, 5, 10, 20, and 40 kPa. The optimized model parameters are in good agreement with previously reported literature values.