COSMO-RS, a general, efficient and easy-to-use methodology for the a priori prediction of thermodynamic data of liquids is applied to several halocarbon mixtures for which recent accurate experimental vapor-liquid- and liquid-liquid-equilibria data are available. Predictions include vapor-liquid equilibria, liquid-liquid equilibria, vapor pressure, gas solubility and solvent-solvent partitioning of refrigerants. The quality and applicability of COSMO-RS in the prediction of thermodynamic refrigerant mixture properties is demonstrated. It is shown that COSMO-RS is an alternative to structure interpolating group contribution methods since it is independent of experimental data and more generally applicable. (C) 2003 Elsevier Science B.V. All rights reserved.