The pressure-temperature (p-T) relation was determined for the decomposition reaction of InN for a pressure range of 6.7-10.0 GPa and a temperature range of 890-1070 K. The decomposition p-T relation was used to calculate the standard enthalpy of formation of InN at 0.1 MPa and 298 K as -36.3 kJ/mol. Furthermore, this p-T relation was used to estimate the decomposition temperature at ambient pressure as 204K, which is significantly lower than those previously estimated from the decomposition data obtained at relatively low pressures and temperatures, but this value does agree with those determined by calorimetric methods. Moreover, solid InN was confirmed to be metastable under ambient conditions. (C) 2007 Elsevier B.V. All rights reserved.