Abstract Calorimetric studies on the behavior of the enthalpy of formation in the tin–antimony system have been carried out at five different compositions (43.3–55 at -% Sb). The enthalpy of dissolution has been determined at 796.15 and 768.15 K. The enthalpy of formation is negative and takes a maximum value (2.906±0.002 kJ mol−1) at 298.15 K for 50 at-% Sb. The molar enthalpy of mixing is more positive than that of formation. On comparing with partial molar enthalpy of mixing, the partial molar enthalpy of formation of tin is shifted to more negative values, while that of antimony to more positive values.