It is of practical and theoretical importance to understand how physico-chemical factors influence the mechanisms of calcium carbonate crystallization. The present paper focuses on the effect of the nature of metallic substrates (stainless steel, soft steel and copper) in the nucleation/growth process of electrochemically deposited calcium carbonate. An in situ experimental procedure based on image analysis was used to observe and characterize the crystals on the polarized surface: their number, the surface coverage and several morphometric parameters were quantified. Experimental results were fitted with a mathematic model based on a diffusion-controlled process that allowed to determine the kinetic parameters of crystallization. The results showed that the nature of the metallic substrate did not act on the crystaline variety of the deposit (calcite) but strongly influences the nucleation/growth process. Copper substrate produced a high number of nuclei and a large surface coverage compared with soft steel and stainless steel where the number of crystals and the surface coverage are lower. Whatever the substrate, the lateral growth rate decreased during the experiment. With stainless steel, the growth was significant and with soft steel the growth of crystals was not homogeneous. (c) 2006 Elsevier B.V. All rights reserved.