The determination of the most probable mechanism function and a numerical method of computing three kinetic parameters (The activation energy ( E), the pre-exponential constant ( A) and the reaction order ( n)) of exothermic decomposition reaction of energetic materials by a single non-isothermal DSC curve obtained with a model CDR-1 instrument with a sealed cell of stainless steel and an open cell of aluminium are reported. The data are fitted to the integral, differential and exothermic rate equations by linear least-squares, iterative, combined dichotomous and least-squares methods, respectively. After establishing the most probable general expression of differential or integral mechanism functions by the logical choice method, the corresponding values of E, A and n will be obtained by the exothermic rate equation.