304 stainless steels are widely used in industry due to their corrosion resistance properties. This steel is covered by a protective film of Chromium oxy-hydroxide and is resistant in many corrosive conditions but some of the acidic solutions such as hydrochloric acid and sulfuric acid can cause uniform and pitting corrosion of its surface. So, in order to decrease the corrosion rate different types of inhibitors added to solution. It has been proved that organic inhibitors containing donor atoms with high electron density such as sulfur, oxygen and nitrogen, are effective inhibitors. Among them those who have both nitrogen and sulfur atoms, are more effective inhibitors. Organic inhibitors protect the metal by adsorption on the metal surface. Benzimidazole and its derivatives are heterocyclic organic inhibitors. This molecule has two hetero nitrogen atom. Benzimidazole molecule has two suitable position for surface bond, one is the nitrogen atom with sp 2 electron pair and the other is an aromatic ring. So adsorption of this molecule on the stainless steel surface under active corrosion condition is favorable. In this research the inhibition effect of benzimidazole, 2-mercapto benzimidazole and 2-hydroxy benzimidazole on the corrosion of 304 stainless steel in 1M H 2 SO 4 solution has been studied by polarization, electrochemical impedance spectroscopy (EIS), mot-schottky, chemical quantum calculations and molecular dynamic simulation. Due to the better effect of 2-mercapto benzimidazole and releasing of Fe 2+ in low over potentials (formation of divalent iron oxide), and softness of 2-mercapto benzimidazole It can be concluded that oxide formed on the 304 stainless steel containing Fe 2+ ion, has inclination to soft behavior Key words: stainless steel, organic compositions, benzimidazole, adsorption, corrosion inhibition.