The nucleation and growth kinetics of electrochemical formation of polyaniline (PAN) have been studied by potentiotatic tep techniques. The initial parts of the current tranients obtained at different media are explained by means of the theory for progressive and intantaneous nucleation and growth. The experimental reults have shown that the formation of the PAN film occure via progreive nucleation following a three-dimentional (3-D) hemipherical growth model with diffuion controlled in the olution of 0.5mol.L^-^1An/0.5mol.L^-^1H2SO4. But in the media of HClO4, the electrodepoition of PAN proceeds favourably through two-dimenional (2-D) nucleation and growth under the kinetic controlled. Multinuclear growth of 3-D nuclei may form a grain porous PAN film. While the lateral growth of 2-D nuclei may be expected to have more uniform and compact arrangement of polymer chains.

Key words: SULFURIC ACID, NUCLEATION, PERCHLORIC ACID, POLYANILINE, GROWTH MECHANISM