In this research, osmotic coefficients of the solutions of CuCl2 + CaCl2 in ethanol at T=298.15 K were measured using isopiestic technique. The experimental osmotic coefficients were used for evaluating the solvent activities and the vapor pressures of the solutions. The solvent activity coefficients were predicted using the ion interaction model of Pitzer and electrolyte non-random two liquid (e-NRTL) model of Chen. The capabilities of the models have been discussed on the basis of standard deviations in osmotic coefficients. The results show that the considered models predict the experimental data in a reasonable level. The role of ternary interaction parameters on the fitting capability of the models has also been discussed. The mean ionic activity coefficients of the studied solute have also been calculated using the above mentioned models. The calculated mean ionic activity coefficients are in good consistency with each other. (C) 2012 Elsevier B.V. All rights reserved.