The electrochemical behaviour of haloperidol (HP) on hanging mercury dropping (HMDE), silver solid amalgam (p-AgSAE) and mercury-rich solid amalgam (r-AgSAE) electrodes was investigated by cyclic and square-wave voltammetry. Density functional theory (DFT) and Monte Carlo simulations were carried out to explain the electrochemical mechanisms of HP reduction that dominated our measurements. The theoretical explanation of our experimental results was based on the molecular structure and adsorption profile of HP on the surfaces of the electrodes. The calculated LUMO and Hirshfeld's charges pointed to the preferential reduction of HP at the carbonyl group. The most representative DFT-calculated HP adsorption energies on silver, p-AgSAE and HMDE, respectively, were -17.3, -25.9 and -28.6 kcal mol(-1). Monte Carlo simulations suggest that HP adsorption is stronger on mercury than on the p-AgSAE surface, explaining the sensitivity order of: p-AgSAE < r-AgSAE < HMDE, which was confirmed experimentally. (C) 2014 Elsevier Ltd. All rights reserved.