Ketosulfone has been evaluated as a green corrosion inhibitor for mild steel in 1 M HCl medium by chemical and electrochemical methods. The effect of Ketosulfone on the corrosion rate was determined at various concentrations and temperature. Polarization measurements reveal that Ketosulfone acts as a mixed-type inhibitor. The adsorption of the inhibitor on the mild steel surface in acid solution was found to obey the Langmuir adsorption isotherm. The activation and thermodynamic parameters of dissolution and adsorption were calculated and discussed. Quantum chemical calculations were calculated and discussed, and it supports the results. SEM images of inhibited strips reveal the likely formation of a protective film.