This study presents the synthesis, structural characterization, and inhibition efficiency of a new sulphur containing Schiff base (4-((thiophene-2-ylmethylene)amino)benzamide) (4-TAB) on mild steel in 1.0 M HCl solution. The inhibition efficiency of the 4-TAB is analysed by using electrochemical analysis, solution assay analysis, and theoretical calculation. Electrochemical impedance spectroscopy and linear polarization resistance results show the highest inhibitor efficiency of 96.8% and 96.5%. respectively. The potentiodynamic polarization measurements indicate a decreasing corrosion rate from 9.104 to 0.481 mm year(-1) by addition of 4-TAB. Theoretical calculations are performed using the density functional theory to further confirm and compare our experimental results. (C) 2018 Elsevier B.V. All rights reserved.