Thermodynamic properties of ternary liquid Al-Ge-Sn alloys have been studied by electromotive force (e.m.f.) technique with a liquid electrolyte at the temperature range from T = (1050 to 1250) K. The results of the e.m.f. examination were compared with our calorimetric as well as with literature e.m.f. data and a good agreement was observed. The comprehensive description of thermodynamic properties of liquid Al-Ge-Sn alloys was performed. Tin-rich alloys have positive deviations whereas germanium-rich alloys have negative deviations from ideal solutions for aluminium. The difference between experimental and calculated by the Bonnier geometric model Delta(mix)G(xs) values is positive and reaches an extremum of 1.06 kJ (.) mol(-1). Positive values of integral excess entropy of mixing at x(Al) > 0.25 can be attributed to a non-configuration contributions. (C) 2004 Elsevier Ltd. All rights reserved.