The heat capacity of natural strontium sulfate - mineral celestine - has been measured over the range of 5-320 K by the method of adiabatic calorimetry and its thermodynamic functions have been determined. The methods of X-ray phase analysis, Raman spectroscopy and electron probe microanalysis have confirmed the adequacy of the sample to mineral celestine. The standard values of thermodynamic functions were: C degrees(p)(298.15) = 100.30 +/- 0.11 J mol(-1) K-1, S degrees(298.15) = 123.44 +/- 0.28 J mol(-1) K-1 and Delta H degrees(298.15) = 18, 406 +/- 33 J mol(-1). The heat capacity and thermodynamic functions of celestine have also been calculated by means of methods of semi-empirical quantum-chemical calculation and the theory of crystal lattice dynamics. (C) 2013 Elsevier B.V. All rights reserved.