Polyaniline has been electrosynthesized on mild steel in a two-step process from aqueous electrolytes. The first step, which acts as a pretreatment of the surface, is the deposition of a thin polypyrrole film. It can be achieved in less than 3 seconds. It is followed by the electrodeposition of a PANI film of controllable thickness. Bilayer systems are thus generated. They show electroactivity in acidic electrolyte similar to that of PANI deposited on platinum, which indicates that the underlying oxidizable metal is fully protected.