AbstractThermodynamic investigations on liquid Au—Pd alloys have been performed by means of a computer‐aided mass spectrometer in combination with a high temperature Knudsen cell unit with improved temperature measurement. A further development of the “Algebraic Intensity‐Ratio”‐method (A.I.R.) has been applied for determining the thermodynamic excess functions. T.A.P.‐series (Thermodynamically adapted power series) with three adjustable parameters are used for the algebraic representation of the thermodynamic excess properties. At 1850 K the molar excess Gibbs energyGEis negative (minimum: — 1300 J/mol at 33.9 at.% Pd) nearly over the whole range of concentration, only the alloys with more than 85 at.% Pd show slight positiveGE‐values (maximum: 78 J/mol at 93.2 at.% Pd). The molar heats of mixingHE, and the molar excess entropiesSEshow at 1850 K a similar behaviour. These quantities are mainly negative; slightly positive values occur only for alloys with more than 70 at.% Pd. The minimumHE‐value is —8220 J/mol (28.7 at.% Pd), and the minimumSE‐value is —3.8 J/mol · K (28 at.% Pd). The maximumHE‐value is 1390 J/mol at 88.15 at.% Pd. and the maximumSE‐value is 0.7 J/mol · K (87.5 at.% Pd). At 1850 K the thermodynamic Au‐activitiesaAuare found to show slight negative deviations from ideality over the whole concentration range. The same behaviour is observed for the Pd‐activities for Pd‐concentrations less than 50 at.‐% Pd. The Pd‐activities of alloys with more than 50 at.‐% Pd show s