A lattice-based model for solutions with solute-solvent association is extended to the calculation of phase equilibria in polymer-CO2 systems in this work. The model is simple to use and requires a maximum of two adjustable parameters to correlate both cloud point and sorption data. Moreover, we show that one of these parameters can be obtained from spectroscopic data. Application of the modified model is demonstrated for the calculation of cloud point curves of seven polymer-CO2 systems. Good agreement with experiment was obtained, with average deviations between calculated and experimental data of 1.3%. The predictive capabilities of the model are demonstrated by calculating the sorption behavior Of CO2 in polymers using parameters from cloud point data. (c) 2004 Elsevier B.V. All rights reserved.