The initial stages of In electrodeposition onto vitreous carbon were studied in chloride solutions by voltammetric and single potentiostatic pulse techniques. The nucleation process was analyzed in terms of the atomistic theory of nucleation. A model based on nucleation on active centers of vitreous carbon, involving adsorption of Cl- on the initially adsorbed indium atoms, is proposed. Experimental results obtained in a wide potential region were interpreted on the basis of this model and conclusions are drawn for the nucleation mechanism in this medium.