The copper electrodeposition process was studied onto different gold substrates, single crystal (1 1 1) and polycrystalline, using electrochemical techniques. It was found, from the analysis of the experimental current density transients, that the potentiostatic formation of a full copper monolayer onto the gold electrode under UPD conditions follows the same mechanism, regardless of the crystallinity of the substrate. The mechanism involved the simultaneous presence of an adsorption process and of two 20 nucleation processes, progressive and instantaneous, respectively. (C) 2011 Elsevier Ltd. All rights reserved.