This paper presents a three-dimensional, three-phase compositional model for simulating CO2 flooding including C02 solubility in water. Both fully implicit and IMPES formulations are included. In this model, C02 is allowed to dissolve in the aqueous phase while all other components except water exist in the oil and gas phases. Oil- and gas-phase densities and fugacities are modeled by a cubic equation of state. The aqueous phase properties are functions of the amount of dissolved C02. C02 solubility is computed using a C02 fugacity coefficient table that is converted internally from input C02 solubility data as a function of pressure at reservoir temperature. Correlations for computing the solubility of C02 in water and other properties of C02 saturated water are presented. Results for simulation runs with and without C02 solubility in water are shown for comparison.