The effect of 1-(benzo[d]thiazol-2-yl)-3-chloro-4-(3,5-dichlorophenyl)-4-methylazetidin-2-one (BDMA) and 3-(benzo[d]thiazol-2-yl)-2-(3,5-dichlorophenyl)-2,5-dimethylthiazolidin-4-one (BDMT) on the corrosion of oil well tubular steel (N80 steel) in 15% hydrochloric acid solution was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The surface morphology of the uninhibited and inhibited samples was studied with atomic force microscopy (AFM). The corrosion inhibition efficiency of both inhibitors increased with increasing inhibitors concentration. The adsorption of both inhibitor molecules on surface of N80 steel obeys Langmuir adsorption isotherm. Potentiodynamic polarization measurements indicated that both the studied inhibitors act as mixed type inhibitor. Quantum chemical calculations were carried out using density functional theory (DFT) to correlate the experimental results with the theoretical results.