Thermophysical and thermochemical studies have been carried out for crystalline parabanic acid. The thermophysical study was made by differential scanning calorimetry, DSC, over the temperature interval between T = (263 and 473) K. Two phase transitions were found: at T = (392.3 +/- 1.6) K with the enthalpy of transition of (2.1 +/- 0.4) kJ . mol(-1) and at T = (509.8 +/- 1.5) K, when the compound was scanned to its fusion temperature. The standard (p degrees = 0.1 MPa) molar enthalpy of formation, at T = 298.15 K, for crystalline parabanic acid was determined using static-bomb combustion calorimetry as -(590.2 +/-1.0) kJ . mol(-1). The standard molar enthalpy of sublimation, at T = 298.15 K, was derived from the variation of their vapour pressures, measured by the Knudsen-effusion method, with the temperature. These two thermochemical parameters yielded the standard molar enthalpy of formation in the gaseous phase, at T = 298.15 K, as -(470.8 +/- 1.2) kJ . mol(-1). (C) 2008 Elsevier Ltd. All rights reserved.