The high-temperature heat capacity of zirconia was directly measured by differential scanning calorimetry between T = (1050 and 1700) K and derived from the heat content measured by transposed temperature drop calorimetry between T = (970 and 1770) K, including the monoclinic-tetragonal (m-t) phase transition region. The enthalpy and entropy of the m-t phase transition are (5.43 +/- 0.31) kJ.mol(-1) and (3.69 +/- 0.21) J.K-1.mol(-1), respectively. Values of thermodynamic functions are provided from room temperature to 2000 K. (C) 2005 Elsevier Ltd. All rights reserved.