Polyaniline (PANI) has been studied for some years in order to protect mild steels against corrosion in the absence of inorganic conversion layers. During the electropolymerization of PANI film, iron is passivated; the subsequent protection is dependent on the nature of this passive layer, and PANI acts as a stabilizer of this layer. The best conditions for PANI electrodeposition are discussed here, using a simple electrochemical test to characterize the passivity breakdown. (C) 2000 The Electrochemical Society. S0013-4651(00)04-070-2. All rights reserved.