This study is focused on modelling the phase equilibrium behaviour of the reaction mixture (CO2 + methanol + DMC + H2O) at high pressure-temperature conditions using the Patel-Teja (PT) and Peng-Robinson-Stryjek-Vera (PRSV) equations of state along with the van der Waals One-Fluid (1PVDW) mixing rule. The optimum values of the binary interaction parameters (k(ij)) were calculated from VLE data found in the literature, and then adjusted to a lineal temperature equation. As a result, the temperature-dependent model was applied to predict the fluid phase equilibria of the corresponding binary a ternary sub-systems and, later, successfully contrasted with experimental data. In addition, phase equilibrium data were experimentally measured at high pressure (8 MPa to 15 MPa) for the ternary system (CO2 + methanol + DMC), in order to confirm the ability of the model to predict the phase behaviour of the ternary system at high pressure-temperature. The agreement between the experimental data and the proposed model enables to predict the phase equilibrium behaviour of the mixture (CO2 + methanol + DMC + H2O), and thus, optimise the operation conditions in several reaction and separation processes. (c) 2006 Elsevier Ltd. All rights reserved.