Enthalpies of formation (Δ f H) of nickel–tin compounds have been measured by direct reaction calorimetry: ΔfHNi3Sn2_LT=−29.0±0.9 kJ mol−1 (approximate value); ΔfHNi3Sn2_HT=−35.0±0.2 kJ mol−1;ΔfHNi3Sn2_HT=−34.3±1.7 kJ mol−1;ΔfHNi3Sn_HT=−21.0±2.4 kJ mol−1;ΔfHNi3Sn_LT=−24.4±1.2 kJ mol−1 and ΔfHNi3Sn4=−29.8±1 kJ mol−1.Standard states are solid Ni and liquid Sn at the respective working temperatures: 728, 1288, 1389, 1332, 943 and 846K.The enthalpy of formation of the Ni 3 Sn high-temperature form is measured for the first time, while that of Ni 3 Sn 2 _LT must be considered as approximate because the corresponding calorimetric reaction was incomplete.The chemical and phase compositions of the specimens have been verified by electron probe microanalyses and by high- and room-temperature X-ray diffraction analyses. Unidentified thermal effects have been observed in the Ni 3 Sn 2 phases region.