The role of Sulfur containing compounds namely: Thiobarbituric acid (TBA) and Thiourea (TH) as corrosion inhibitors for mild steel in 1 M HCl has been studied using potentiodynamic anodic polarization, electrochemical impedance spectroscopy, atomic force microscopy and scanning electron microscopy techniques. Polarization results showed that all the compounds studied are mixed type inhibitors. Electrochemical impedance studies showed that the presence of these compounds decreases the double-layer capacitance and increases the charge transfer resistance. Quantum chemical calculation was further applied to reveal the adsorption structure and explain the experimental results. The results of calculations showed superior inhibition efficiency of TH in comparison to TBA.