Mixtures containing strong electrolytes, e.g. salts, or systems with weak electrolytes, e.g. acid gases, are present in many applications and therefore electrolyte thermodynamics is of importance in many contexts and diverse fields such as:. CO 2 and H 2 S removal by absorption using aqueous solutions of alkanolamines and ammonia. . Novel solvents such as ionic liquids. . Pharmaceuticals, amino acids, proteins and other applications in biotechnology. . Corrosion in wet gas pipelines. . Scale formation in oil production and in heat exchangers. . Production of fertilizers using ion exchange and salts.Despite its importance and even the fact that certain aspects are somewhat controversial (e.g. discussion about standard states, measurements of single ion activity coefficients, Lewis-Randal vs. McMillan-Mayer framework), relatively less attention has been given to modeling electrolyte mixtures compared to nonelectrolyte thermodynamics.A review of electrolyte thermodynamics has been presented by Loehe and Donohue 1 , covering theories and models in the period 1985-1997. Prausnitz et al. 2 discussed the fundamentals of electrolyte thermodynamics as well as local composition models also with applications to gas solubility and biotechnology. Local composition models are presented also in the short review by Pinsky and Takano 3 , which includes computational details of a few key activity coefficient models. The recent reviews by Lin et al. 4 and Tan et al. 5 include discussions on electrolyte equations of state, with special emphasis on those combining SAFT theory and electrolyte theories. Finally, the electrolyte chapter in Michelsen and Mollerup 6 contains a full derivation and discussion from a modern perspective of the Debye-H€ uckel theory, as well as standard states and theories for dipolar ions (Kirkwood theory). Full derivatives and computational aspects are also presented.