Over the last few years, the classic synthesis of benzimidazoles has low yields and through complex routes. In the past thirty years organic thermochemistry has developed rapidly and led to a wealth of novel reactions and applications that can be of great significance. The present work has been devoted to study of thermal fragmentation of aromatic and heterocyclic amidoximes I-VI at 220-240oC alone and /or in the presence of naphthalene and tetralin as radical scavengers. The main feature of these thermolyses is the homolysis of the N-O and C-N bonds initiating different free radical reactions. These studies have been led to the formation of novel synthesis of a variety of heterocyclic compounds like; benzimidazole derivatives as the major products (45-60 %) in addition to benzoxazoles, carbazoles and triazine as the minor products. such reactions in an effort to gain further information about more generalized thermolytic mechanism to account for the identified products. In addition to the aimed synthetic value of the work, mechanistic studies and environmental applications are also targeted.