Abstract The thermodynamic properties of liquid Ag–Sb –In alloys were determined using solid oxide galvanic cells with zirconia electrolyte. The following galvanic cells were employed: in the temperature range from 973 to 1200 K. (I) R e + kanthal, A g x − I n y − S b ( 1 − x − y ), I n 2 O 3 / / Z r O 2 + Y 2 O 3 / / N i O , N i , P t $$\begin{array}{l}\mathrm{Re}+\text { kanthal, } \mathrm{Ag}_{x}-\mathrm{In}_{y}-\mathrm{Sb}_{(1-x-y),} \\ \mathrm{In}_{2} \mathrm{O}_{3} / / \mathrm{ZrO}_{2}+\left(\mathrm{Y}_{2} \mathrm{O}_{3}\right) / / \mathrm{NiO}, \mathrm{Ni}, \mathrm{Pt}\end{array}$$ Thermodynamic properties of the liquid phase were described by the Redlich – Kister –Muggianu formula and the phase relations in the ternary system were calculated. The results of the calculations were compared with experimental data available from different literature sources.