The exchange of oxygen between carbon dioxide and carbon monoxide that occurs reversibly on carbon surfaces was studied at temperatures of 750 deg. to 850 deg. C and a pressure of 1 atmosphere. Carbon-14 was used to detect and measure the exchange reaction. The extent of oxygen exchange was a linear function of composition of the gas mixture, and this relationship was used to evaluate the forward and backward rate constants of the reaction. Equilibrium constants, directly determined for oxygen exchange in this study, agreed well with values in the literature that were derived only by indirect procedures. This result establishes the validity of oxygen exchange in the mechanism of carbon gasification by co2. Rates of carbon gasification were less than an order of magnitude slower than rates of oxygen exchange. Activation energies for these two processes were 58 and 53 kcal/mole, respectively. The closeness in the activation energies argues against any change in the rate-controlling step over a wide temperature span at atmospheric pressure. The role of CO as a retardant on the co2-c reaction and the nature of the carbon-oxygen complex are also discussed.