Abstract The partial and integral enthalpies of mixing of Al–Fe–Ge melts have been measured by high-temperature calorimetry at 1740 ± 5 K. The integral enthalpies of mixing at 1173 K, are about 4 to 6 kJ mol–1 less negative than determined by electromotive force measurement [9]. The integral enthalpies of mixing have been also estimated on the basis of the Bonnier geometric model. The calculated values show a reasonable agreement with experimental data for x Ge > 0.3. A difference between experimental and estimated integral enthalpies of mixing (up to 2.5 kJ mol–1) is observed for ternary alloys with low germanium content.