Electrocopolymerization of a binary mixture of 3-chloroaniline and 2-amino-4-phenylthiazole on platinum electrode in acid medium was carried out under different reaction conditions such as temperature, current density, hydrochloric acid, and monomer concentrations with duration time. The initial rate of the electrocopolymerization reaction on platinum electrode is small and the rate law is RP = K-2 [D](1.29)[HCl](0.97)[M](1.94). The apparent activation energy is found to be 38.87 kJ/mol. The obtained copolymer film is characterized by H-1-NMR, elemental analysis, GPC IR, UV-visible, and cyclic voltammetry and compared with those of the two homopolymers. The mechanism of the electrocopolymerization reaction is also discussed and the monomer reactivity ratio (r(1) and r(2)) is calculated. The thermogravimetric analysis (TGA) is used to confirm the proposed structure and determination of the number of water molecules in the polymeric chain unit. X-ray and scanning electron microscopic analysis are used to investigate the surface morphology. (C) 2005 Wiley Periodicals, Inc.