The article shows results of FT-IR and 1H NMR study for azeotrope diethyl amine–acetone. Changes in chemical shifts and vibrational frequencies for pure diethyl amine, pure acetone and their azeotrope were obtained. The unit-structure of cluster has been suggested on the basis of mole ratio, boiling point depression for azeotrope of diethyl amine and acetone, and comparison between the spectra obtained by FT-IR and 1H NMR techniques.