Pulse galvanostatic method is used to synthesize polyaniline (PANI) in HNO3 solution. Scanning electron microscopy results show that PANI prepared in this article has a nano-fibular structure. The influences of the synthesis parameters, such as mean current density, the ratio of 'on' to 'off' period (t(on)/t(off)), pulse frequency, monomer concentration and reaction temperature, on the morphology and the electrochemical properties of the PANI films have been investigated. The electro-activity of PANI film strongly depends on the morphology, which is determined by preparation conditions. At the following conditions, mean current density 1-3 mA cm(-2), t(on)/t(off) 10, frequency 10 Hz, monomer concentration 0.4 M and temperature 20 degreesC, the high quality nano-fibular PANI film with the best electrochemical properties can be obtained. (C) 2003 Elsevier B.V. All rights reserved.