Abstract: The growth of nano-fibrous polyaniline (PANI) film on stainless steel (SS) by pulse galvanostatic method (PGM) in 0.3 mol•L^-1 aniline +1 mol•L^-1 HNO₃ aqueous solution at 1 mA•cm^-2 was studied. The electrochemical behavior during the polymerization and the morphology of the PANI films with various deposition charges were characterized by chronopotentiogram and scanning electron microscope (SEM), respectively. Moreover, the rate of aniline electropolymerization was determined by the cyclic voltammetry (CV) technique. The results showed that the polymerization of aniline on SS involved two separate stages. Firstly, polyaniline grew on bare SS electrode and represented granular structure. In this stage, the potential of aniline polymerization was relatively positive (at ca. 1.10 V). After about 30 s, the surface of the SS electrode was entirely covered by a granular PANI film. Secondly, PANI grew further with nano-fibrous morphology on the surface of the granular PANI film. The polymerization potential maintained ca. 0.75 V when the granular PANI film was entirely covered by the nano-fibrous PANI film.

Key words: Polyaniline, Pulse galvanostatic method, Growth process, Morphology