Silver electrodeposition onto HOPG electrodes in the presence of picolinic acid (PA) has been studied by cyclic voltammetry and chronoamperometry. Changes in the nucleation and growth mechanisms, which are dependent on the PA concentration and solution pH, have been observed. Formation of complexes with Ag+ ions and adsorption of the additive molecules on both, the substrate and the growing silver crystallites can be correlated with the potential dependence of the kinetic parameters, N-0 and A. The amount, distribution (random or localized on the defects sites) and size of the crystallites on the substrate are influenced by the composition of the solution (PA concentration and pH) when the control of the nucleation and growth processes is regulated by application of a double potential program. (C) 2012 Elsevier B.V. All rights reserved.