The solubilities of carbon dioxide in methanol and in methanol-water mixtures have been measured at 243, 258, 273, and 298 K, and at pressures up to 54 atm. An extended Soave-Redlich-Kwong equation of state with Mathias' polar correction factor has been used to describe the equilibrium behavior of these mixtures. Binary interaction parameters were evaluated using data from these experiments, as well as those found in the literature. Correlations of the binary data using this equation of state were excellent. Use of the parameters from the binary correlations to predict solubilities of carbon dioxide in mixtures of methanol and water resulted in favorable agreement with the experimental data over most of the system conditions. However, at high concentrations of carbon dioxide, the equation tended to predict the formation of two liquid phases. This tendency is thought to be related to the mixing rules used in formulating the equation of state. (Copyright (c) 1985 Elsevier Science Publishers B.V.)