Heat capacities of liquidn‐heptane, that is the recommended calorimetric reference material, have been converted to the International Temperature Scale of 1990 (ITS‐90) and new reference data have been generated. Raw experimental data measured at the National Bureau of Standards, Washington and at the Bureau of Mines, Bartlesville have been critically selected from a large compilation of liquid heat capacity data. A joint correlation of the converted data has been performed. Sets of reference data are presented for both the saturation and the isobaric heat capacities in the range fro 182.6 to 480 K. Parameters of a correlating equation and tables of heat capacities are provided.