This work was concerned with developing an accurate model for the prediction of thermodynamic properties of mixtures of refrigerants. That model was the extension to mixtures of a recent work by the author about a Helmholtz and extended corresponding states model for refrigerants. In the proposed model the residual Helmholtz energy of the mixture was expressed as the contribution of three terms: one from an extended corresponding states model and the other two were corrections in terms of one-fluid mixing rules of functions of reduced temperature and density. The extended corresponding states model was based on the temperature- and density-dependent shape factors that the author has presented previously in the literature and the reference fluid was R-32 with properties calculated with the Tillner-Roth and Yokozeki reference equation of state. The fluids of interest were six binary systems and two ternary systems: (R-32 + R-125), (R-32 + R-134a), (R-125 + R-134a), (R-125 + R-143 a), (R-134a + R-143 a), (R-134a + R-152a), (R-32 + R-125 + R-134a) and (R-125 + R-134a + R-143a). The following were the obtained percentage overall average absolute deviations: 0.347 in p rho T data, 1.836 in isochoric heat capacities, 1.108 in isobaric heat capacities, 0.073 in speeds of sound, 0.467 in bubble-point saturation pressures and an overall average absolute difference of 3.367 cm(3) mol(-1) was obtained in second virial coefficients. These results compared satisfactorily with those from other models for mixtures of refrigerants. (C) 2014 Elsevier B.V. All rights reserved.