Silver passivation is studied in sodium chromate aqueous solutions. It is shown that the active-passive transition involves active metal dissolution followed by the precipitation of a poorly-conducting layer of silver chromate that passivates the electrode. The potentiodynamic current-potential behavior is adequately described by using the layer-pore-resistance model (LPRM). The agreement between experimental and theoretical curves is excellent and allows us to demonstrate that, after the first stages that involve active dissolution of silver and nucleation of the film, the growth of the passive layer is mainly controlled by the resistance of the electrolyte in the pores of the layer. After passivation, further growth of the film occurs under diffusion control.