The Arrhenius type reaction rate parameters for the initiation reactions governing the thermal decomposition of several energetic ionic liquids (EILs) were determined by numerical techniques The compounds chosen for this purpose were the energetic 4 amino 1,2,4 triazolium nitrate (4ATN) and 1 hydroxyethyl hydrazinium nitrate (HEHN) The supplementary compounds studied for comparison were 4 amino 1 2,4 triazolium chloride (4ATCl) and ammonium nitrate (AN) The reaction rate parameters were obtained by an evolutionary genetic algorithm (GA) that compared the difference between the experimental and simulated species evolution profiles from the decomposition pro cess The experimental data were generated by confined rapid thermolysis (CRT) The decomposition process was simulated by applying conservation equations to the condensed and gas phases individually The optimization module recovered the ex perimental species profiles with reasonable accuracy for all the compounds studied The processes governing the decomposition of these energetic compounds were found to be autocatalytic in nature and the autocatalytic agents were the strong acids generated by the initial decomposition step The activation energy and pre exponential factor for the unimolecular decomposition step for 4ATN HEHN, and 4ATCl were 167-188 kJ mol(-1) and 10(16) s(-1), respectively, similar to previously determined values for AN