The study and characterization of aqueous solutions are becoming an important research topic because of their central role in many processes. The modeling of these solutions is complicated by different factors: the important number of ionic and nonionic species, the nonideality of aqueous solutions, the appearance and disappearance of thermodynamic phases (solid, vapor) depending on operating conditions. This article presents a general model in dynamic state of aqueous electrolytic system involving liquid, vapor, and solid phases. The mathematical formulation includes: physical and chemical equilibria, mass and energy balances, electroneutrality equation and evaporation equation. The set of equations is solved by the Gear's method. The model is validated by the comparison between modeled results (activity coefficients, solubility, evaporite sequence) and experimental data. One of the purposes of the model will be the simulation of a production process of salt crystals and waters concentrated in minerals of interest. (C) 2012 American Institute of Chemical Engineers AIChE J, 2012