The thermodynamic properties of liquid (Sb + Sn) and (Au + Sb + Sn) alloys were determined using solid oxide galvanic cells with zirconia electrolyte: Re + kanthal,Sb-x - Sn(1-x), SnO2//ZrO2 + (Y2O3)//NiO,Ni,Pt, (I) Re + kanthal,Au-x - Sb-y - Sn(1-x-y),SnO2//ZrO2 + (Y2O3)//NiO,Ni,Pt, (II) over the temperature range from (973 to 1273) K. Using the Gibbs free energy of formation of pure solid tin oxide SnO2, at first the activities of tin were determined in the binary (Sb + Sn) system. Next, measurements were conducted in the ternary (Au + Sb + Sn) system along two cross-sections specified by the ratio of mole fractions x(Au)/x(Sb) = 1:2 and 2:1. Thermodynamic properties of the liquid phase were described by the Redlich-Kister-Muggianu formula. In this procedure, the heat of mixing determined in our previous paper was included. The results of the calculations were compared with the experimental values obtained for this system. (C) 2015 Elsevier Ltd. All rights reserved.