Ionic solutions are set apart from molecular solutions by the intervention of Coulombian forces between electrical charges. Numerous models of ionic solutions have been put forward in the existing body of literature. The most important of these models, which is actually found to be included in all the others, is Debye and Huckel's, which attributes the imperfection solely to the electrostatic forces between the ions but, in spite of this, is acceptable only for fully‐dissociated strong electrolytes and very‐dilute solutions. Pitzer's model is a semi‐empirical model based on Debye and Hückel's extended law, where additional terms have been introduced in order to take account of the effects of the ionic strength on the binary interactions over a short distance. The UNIQUAC part of the model can be extended to the UNIFAC version in order to enhance the model's predictive capability.