Abstract: 5 - Acetylamino - 6 - nitorbenzofaroxan (e) and 7- acetylamino benzodifu-roxan(j)have been synthesized for the first time from m-chloroaniline and m-dich-loroaniline through four steps of reaction, i.e . acetylation, nitration, azidation and pyrolysis . The molecular structures of (e) and (j) have been determined applying methods of elemental analysis, IR, NMR and MS spectroscopy . With the technique of differential thermal analysis (DTA) were obtained the kinetic parameters of thermal decomposition of (e) and (j) : their activated energy E , pre- exponential factor A and rate constants k .