The inhibitive action of dicyclohexyl thiourea (DCHTU) on corrosion of mild steel in 3.5% NaCl (3.5% NaCl) has been studied using weight loss, gasometric measurements, potentiodynamic polarization and impedance studies. The studies clearly indicated that DCHTU acted as cathodic inhibitor. The adsorption of the compound on mild steel surface obeyed Temkin's adsorption isotherm. Diffused reflectance spectra and SEM images confirmed the formation of adsorbed film of inhibitor on metal. The quantum chemical analysis substantiates the inhibition efficiency of the compound determined by electrochemical methods.