A new thermodynamic model was presented to calculate the phase equilibria for the oxygen-water system. The modified Redlich-Kwong equation of state with a new correlated cross-interaction parameter was used to calculate fugacity coefficients for the vapor phase. The dissolved oxygen followed Henry's law. A new expression was correlated from the experimental data to calculate Henry's constant of oxygen. The calculated results of equilibrium composition were compared with the available experimental data and those calculated by other models with different parameters. The comparison revealed that the new model is suitable for calculating both liquid and vapor compositions while the empirical method is only suitable for estimating the liquid composition. Furthermore, compared to the model proposed by Rebenovich and Beketov, the calculated results of the vapor composition with the new model are better. (C) 2004 Elsevier B.V. All rights reserved.