Partial and integral enthalpies of mixing of liquid Ga-In-Zn alloys at a temperature of 720 K were measured by high-temperature drop calorimetry. Calorimetric measurements were performed along four intersections as follows: x(Ga)/x(Zn) = 3/1, x(Ga)/x(Zn) = 1/1, x(Ga)/x(Zn) = 1/3 and x(Ga)/x(Zn) = 1/3. Based on obtained thermodynamic results and those available in the literature the thermodynamic optimization was done using Thermo-Calc software. Next, the phase equilibria in the binary and ternary systems were calculated and the results were compared with those obtained using different experimental techniques. (C) 2020 Published by Elsevier B.V.