In this article, a novel and non-toxic Schiff base containing multi-heteroatom coded with the name 5-DAT (5-(4(diethylamino)benzylidene)amino)-1,3,4-thiadiazole-2-thiol is designed as the corrosion inhibitor for mild steel (MS) in 1.0MHCl. The structure of Schiff base is illuminated by NMR, FT-IR, UV spectrophotometers and theoretical (Gaussian and Monte Carlo) calculations. Electrochemical techniques were utilized to determine the inhibition efficiency of synthesized Schiff base on mild steel corrosion. The surface of the MS was characterized by scanning electron microscopy. The inhibition talent of the 5-DAT was described by electrochemical impedance spectroscopy, lineer polarization resistance, and potentiodynamic polarization techniques. 5-DAT synthesized in this study showed high efficiency with 98.9% inhibition efficiency since it contains high electron density heteroatoms such as nitrogen, sulfur and many multiple bonds, which are considered as more adsorption centers compared to the previous ones. While 5-DAT shows efficiency at 298 K, according to EIS and LPR results, respectively, 98.41, 98.12; Itwas observed that the efficiency was not lost much with 93.87, 92.86 efficiencies at 328 K. The presence of a 5-DAT film, which is homogeneously dispersed on the surface, protects the metal surface against corrosion. (C) 2021 Elsevier B.V. All rights reserved.