The partial and integral enthalpies of mixing of binary liquid Ag–Pd alloys (with compositions up to about 55 at.% Pd) were determined at 1400 °C. A Calvet type microcalorimeter was used for the measurements employing a drop calorimetric technique. Additionally, eight sections in the Sn-rich corner of the ternary Ag–Pd–Sn system, which is relevant for lead-free soldering, were investigated at 900 °C. The ternary interaction parameters were fitted using the Redlich–Kister–Muggiano model for substitutional solutions. The isoenthalpy curves for Ag–Pd–Sn at 900 °C were constructed for the integral molar enthalpy of mixing.