Heat capacities and enthalpy increments between the temperatures T approximate to 5 K and T approximate to 380 K were measured with adiabatic calorimetry for pyrazine. The triple-point temperature, enthalpy of fusion, heat capacities, and derived thermodynamic functions are reported for the solid and liquid phases. Three solid-to-solid phase transitions were observed, and the transition temperatures and enthalpies are reported. All results are compared with literature values. The adiabatic calorimetric results reported here provide key quantities required for thermodynamic consistency analyses, which can provide needed validations for calculational techniques (ab initio, semi-empirical, statistical, group contribution, etc.). Such validations are currently lacking for polyazines, such as pyrazine. (C) 2003 Elsevier Science Ltd. All rights reserved.