This article presents an analytical method for the calculation of the adiabatic time to maximum rate. The procedure is developed considering a thermal decomposition process described by a simple n-order kinetic and is based on the introduction of a special function that is possible by integrating analytically. The application of the method requires the knowledge of the thermokinetic parameters of the process under study and allows the calculation of the adiabatic time to maximum rate without the numerical integration of the heat and mass balance equations or the use of relationships based on particular simplifying hypotheses. Its validity has been demonstrated considering numerical and real experiments (thermal decomposition of trityl azide) providing in both cases times to maximum rate values which are very close to the real ones. (c) 2017 American Institute of Chemical Engineers AIChE J, 63: 172-179, 2018