The thermodynamic properties of liquid Ag-Au-Ga alloys were determined using solid oxide galvanic cells with zirconia electrolyte: W, Ag(x)Au(y)Gn((1-x-y)), Ga2O3//ZrO2 + (Y2O3)//FeO, Fe, W (I) in the temperature range from 1023 to 1348 K. Measurements were conducted in the ternary Ag-Au-Ga system along three cross -sections specified by the ratio of mole fractions x(Ag)/x(Au) = 1:2, 1:1 and 2:1. Thermodynamic properties of the liquid phase were described with the Redlich-Kister-Muggianu formula. In this description procedure, the heat of mixing determined calorimetrically in the previous work was included. The results of the calculations were compared with the experimental data obtained in this work.