This paper presents a method to predict the solubility of CO2 in heavy oils and bitumens, as well as the density of CO2-saturated heavy oils and bitumens using a modified three-parameter Martin equation of state. A generalized constant value of the adjusted critical compressibility is suggested in this methodology for the prediction of CO2 solubility and CO2-saturated liquid density. The CO2 solubility in heavy oils and bitumens and their saturated liquid density predictions were compared with several sets of experimental data reported in the literature. The solubility prediction is as accurate as that predicted by the Peng-Robinson equation of state. However, saturated liquid density prediction using the modified Martin equation of state is superior to the Peng-Robinson equation of state.