From quantum mechanical calculations, based on density functional theory and using the pseudopotentials plane-wave method, in the first part of this work, a set of iron surfaces namely: (1 1 0), (1 0 0), (1 1 1) and (3 1 1) have been modeled and their work functions and surface energies calculated. It was found that the Fe(1 0 0) surface displayed the highest surface energy (2.43 J m(-2)), the lowest work function (3.95 eV) and the lowest coordination number too, thus furnishing the conditions for the interaction with the organic molecule. In the second part, the bonding structure for 2-mercaptoimidazole, 2MI, adsorbed onto Fe(1 0 0) surface has been studied and the geometry optimized; the adsorption energy (-1.26 eV), the Bader analysis and the bonding structure are presented and discussed. In these calculations, different adsorption sites of the Fe(1 0 0) surface, such as top, bridge and hollow were considered. The energetically most favored adsorption geometry shows the aromatic 2MI ring in a parallel position with respect to the surface, the charge transfer flows from the metallic surface to the inhibitor mainly through the adsorbate's carbon and sulfur atoms. Two dissociation processes were found: one related to deprotonation of the thiol group, and the other to releasing the entire thiol group. They were lower in energy by about 033 eV and 1.42 eV, respectively, than the adsorption energy of the molecule as a whole. (C) 2013 Elsevier Ltd. All rights reserved.