Inhibition performance of 2,2'-diaminodiethyl disulfide (DA) was studied against mild steel (MS) corrosion in 0.5 M HCl. Electrochemical impedance spectroscopy (EIS), potentiodynamic (PD) polarization measurements were utilized to investigate the influence of inhibitor concentration and temperature on efficiency, as well as explanation of inhibition mechanism. Scanning electron microscopy (SEM) analysis was utilized to investigate the surface damages due to corrosion, in the absence and presence of inhibitor molecules. PD data revealed that the studied molecule exhibits mixed type inhibitor behavior on steel surface. Moreover, the calculated free adsorption energy (Delta G(ads)(o)) value is 38.45 kJ mol(-1), which indicates to strong adsorptive interaction by both physical and chemical means. UV-Visible study results supported the idea that there is strong interaction between the surface with the molecule, via its -S and -N atoms. As a consequence, 91.7% inhibition efficiency was determined in presence of 1.0 mM DA. (C) 2020 Elsevier B.V. All rights reserved.