The thermal decomposition of 3,5-dinitro-4-methylbenzoic acid is studied by means of differential calorimetric techniques (DSC). Its autocatalytic behaviour has been highlighted and the decomposition process has been described considering the generalized expression of the Sestak-Berggren model. A new procedure for the optimization of the initiation parameter along with the other Arrhenius constants and kinetic exponents starting from the knowledge of the classic Sestak-Berggren model is illustrated. Encouraging results point out the validity of the approach which has been verified considering both a series of numerical and real experiments. (C) 2015 American Institute of Chemical Engineers