Passivation of iron in phosphate medium was studied by voltammetry and X-ray photoelectron spectroscopy. The voltammetry at low sweep rate has permitted us to determine the different stages of the passivation. The process of electrochemical passivation obeys a dissolution-precipitation mechanism. The film growth is controlled by the resistance of the solution in the pores. The electrochemical impedance measurements show that the passive film on iron is an n-type semiconductor, highly doped (N-D = 4.69 x 10(20) cm(-3)) and its flat-band potential was equal to -570 mV/(SSE). The composition depth-profile of the passive film was measured by sequential use of XPS and sputter etching. It was found that the film consisted mainly of both metallic oxides and phosphate.