© 2019 American Chemical Society. Ionic liquids (ILs), which are also known as liquid salts or ionic fluids, are organic salts with a low fusion point. They behave as a liquid at low temperature or ambient temperature. Accordingly, they are prominent solvents to be used in the green chemical processes, because of their attractive physicochemical properties such as low vapor pressure, high thermal stability, an excellent solvation behavior, and high gas solubility. Recently, various experimental researches have reported the water solubility in different imidazolium-based ILs at different temperature, pressure, and composition conditions. In this study, we present the modeling of the vapor-liquid equilibrium of the H 2 O-IL system using the Peng-Robinson cubic equation of state (EoS), coupled with the Wong-Sandler mixing rules; eight binary systems were studied for this purpose. In addition, improved temperature-dependent parameters were introduced into the EoS as those proposed by Stryjek and Vera for water [Can. J. Chem. Eng. 1986, 64, 323] and by Yokozeki for the IL [Int. J. Thermophys. 2001, 22, 1057]. The studied ILs were [C x MIM][Cl] (x = 2, 4, 6), [C 4 MIM][PF 6 ], [C 2 MIM][BF 4 ], [C 4 MIM][BF 4 ], [OHC 2 MIM][BF 4 ], and [OHC 2 MIM][Cl]. The obtained results showed a satisfactory agreement between the experimental and the calculated solubility data using the present modeling approach under different conditions of temperature, pressure, and composition.