Iron nucleation mechanisms from aqueous solutions onto vitreous carbon electrode were comparatively investigated in iron sulfate and iron chloride systems by utilizing the electrochemical techniques of cyclic voltammetry (cv) and chronoamperometry (ca), coupled with atomic force microscopy (AFM) studies. The investigated parameters were pH, scanning rate, iron concentration, deposition potential and temperature. It was found that iron nuclei population density decreased with increase of pH. On the other hand, the population density increased with increase of iron concentration and cathodic deposition potential. Increase of solution temperature resulted in the increase of nuclei population density in the sulfate system, while the dependence of nuclei population density on temperature in the chloride system was more complex. The experimental electrochemical data fitted the theoretical model describing progressive nucleation mechanisms, which was also confirmed by the AFM morphological studies. In addition, the atomic force microscopy was successful in determining the possible crystallographic orientations of electrodeposited iron nuclei. (c) 2005 Elsevier Ltd. All rights reserved.