The aim of this research study was to apply experimental design in the optimization of influencing parameters on the corrosion inhibition efficiency of 2-(2-hydroxyphenyl)-benzothiazole using electrochemical impedance spectroscopy (EIS). By experimental design, the best measurement for a mixture of 2-(2-hydroxyphenyl)-benzothiazole and ethanol as an impressive corrosion inhibitor for the mild steel in different hydrochloric acid concentrations through studying the surface reaction procedure was investigated. Obtained optimum values by response surface methodology (RSM) were 433.7 mu M for inhibitor concentration, 3.38 M for hydrochloric acid, and 0.36 M for ethanol concentration.