Enthalpy increments Of U0.45Pu0.55N were measured in the temperature range of 1025-1775 K by inverse drop calorimetry using a high temperature differential calorimeter. The enthalpy increments were fitted to a polynomial in temperature and the heat capacity, entropy and Gibbs energy functions were computed. The results are presented and discussed in comparison with literature data. (c) 2007 Elsevier B. V. All rights reserved.