The corrosion is an (unwanted) reaction of materials with substances present in their environment. In the case of iron this reaction becomes visible for instance when rust forms. The reasons for this corrosion are diverse and are covered very extensively in the literature. The study of corrosion processes and their inhibition by organic inhibitors is a very active field of research. The presence of actives centres in the molecular structure has a major effect on the inhibition efficiency and consequently on the phenomenon of adsorption on some metals surface. The inhibition effect mainly depends on some physicochemical and electronic properties of the inhibitor which relate to its functional groups, steric effects, electronic density of donor atoms, and orbital character of donating electrons. Corrosion inhibition of has been elucidated by means of theory DFT-derived reactivity indexes. The calculated quantum chemical parameters have already proven to be very useful in determining the molecular structure as well as elucidating the electronic structure and reactivity. Thus, it has become a common practice to carry out quantum chemical calculations in corrosion inhibition studies.