Equilibrium data were obtained for aqueous two-phase systems composed of ionic liquid (IL) and two inorganic salts (dibasic potassium phosphate, K2HPO4, and tripotassium phosphate, K3PO4) at 298.15 K. The evaluated ionic liquids were 1-butyl-3-methylimidazolium methanesulfonate ([C(4)mim][CH3SO3]), 1-butyl-3-methylimidazolium chloride ([C(4)mim][Cl]), and 1-ethyl-3-methylimidazolium chloride ([C(2)mim][Cl]). Equilibrium curves of salt and ionic liquid were determined. Additionally, each curve was fitted into three mathematical models. The aqueous two-phase system composed of the IL [C(2)mim] [Cl] required a lower mass fraction of IL and salt to form the systems than the other two systems studied in this work containing [C(4)mim] [Cl] and [C(4)mim][CH3SO3]. Furthermore, the type of inorganic salts studied did not affect the equilibrium curves for the same ionic liquid.