Results of experimental thermodynamic analysis of binary systems Ge-Ga and Ge-Sb obtained by Oelsen calorimetry are presented in this paper. Activities, activity coefficients, partial molar quantities for both components in the investigated systems at temperatures 1073, 1173 and 1273 K are determined. Also, integral mixing enthalpies in the temperature interval 350-1300 K are determined and given in the enthalpy isotherm diagram.