The electronic parameters of plain 1,2,4-triazole and three isomeric forms of amino-1,2,4-triazole have been studied at the B3LYP/6-31G(d, p) level of theory. Their inhibitory effectiveness was investigated by means of chemical reactivity parameters and reactive centers were analyzed on the basis of Fukui indices. The solvent effect on the studied parameters was found to be insignificant. 3-amino-1,2,4-triazole (3-ATA) with preferred corrosion inhibition performance possesses two electrophilic and two nucleophilic attack centers, implying multicenter adsorption of the molecule on a metal surface. Its interaction with the Cu atom is dominated by the electron donation from the Cu atom to the carbon atom C3 and the back-donation from the amino atom N6. (C) 2009 Elsevier B. V. All rights reserved.