In this thesis, two main objectives are followed. In the first aim, the structures of the different tautomers of tetrazole 5-thion on the (111) and (110) of Cu surface were optimized, separately and the preferred orientations of the tautomers relative to the considered surfaces were determined. It should be mentioned that the calculations were performed on the five tautomers of the tetrazole 5-thion, separately. It was determined the adsorption on the surfaces is physically, but in some cases the chemisorption accompanied with the proton transfer from the tautomer to the surface were observed. The values of the adsorption energies (?Ead), pure adsorption energies (?Ead-WD) and deformation energies for the surface and the tautomer (EDef ) were calculated for all adsorption cases. In the second aim, the effects of the tautomers on the inhibition of the corrosion of the copper were studied using quantum chemical calculations. For this purpose, the energies of the HOMO and LUMO of the cases and their shapes were calculated. The discussions on the effect of the tautomers on the inhibition of the corrosion of the copper were performed based on the energy gap of the HOMO and LUMO and also their shapes. In addition, the fraction of electron transferred from the inhibitor to metallic surface was calculated using the quantities such as electron affinity and ionization energies.