The purpose of this study is to select an appropriate thermodynamic model among the ones available in commercial process simulators for representing the phase behavior of the carbon dioxide + ethanol + water system. The following versions of the Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) cubic equations of state (EoS) were considered: Panagiotopoulos-Reid, modified Panagiotopoulos-Reid, Huron-Vidal-NRTL, Modified Huron Vidal (MHV2-UNIFAC), Predictive Soave-Redlich-Kwong (PSRK) and Volume-Translated Peng-Robinson (VTPR). The Polar Perturbed-Chain SAFT EoS deriving from the Statistical Associating Fluid Theory (PPC-SAFT) was also selected for the present investigation. This study highlighted that the optimal thermodynamic models for the application of interest have to be chosen among the VTPR, PSRK and MHV2-UNIFAC EoS. Once identified a suitable thermodynamic model for the CO2 + ethanol + water ternary system, it has been possible then to simulate the extraction process of polar compounds from natural products and to discuss how water influences the process efficiency.