Object: Synthesis of N-acylbenzotriazoles to create a series of organic compound containing carbonyl group which can be easily converted into heterocyclic compounds, bio-active compounds such as: hormones, vitamins, amino acid... Subjects and research method: reaction between carboxylic acid, thionyle chloride and benzotriazole in anhydrous solvent at room temperature under inert pressure provides the N-acylation compound.