The LIQUAC model is widely used to predict reliably vapor-liquid equilibria (VLE), osmotic coefficients and mean ion activity coefficients for electrolyte systems. It consists of a Debye-Huckel term, the UNIQUAC term and the osmotic virial equation for the middle-range contribution. The aim of this work is to provide a model based on the group contribution concept that can be used to predict phase equilibria in mixed-solvent electrolyte systems. Therefore, in the LIQUAC model the UNIQUAC equation has been substituted by the original UNIFAC equation and group interaction parameters have been introduced into the middle-range term. With the help of a large data base, 234 group interaction parameters for seven solvent groups, 13 cations and seven anions have been fitted. The model parameters have been used to calculate the VLE behavior, osmotic coefficients and mean ion activity coefficients for a large number of systems with high accuracy.