In this paper, copolymerization of diphenylamine with p-phenylenediamine was carried out in aqueous sulfuric acid by means of cyclic voltammetric sweep. The obtained copolymer was characterized by cyclic voltammetry (CV), Fourier transform infrared (FTIR), CHNS, energy-dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Electrochemical experiments indicated that the copolymer modified electrode exhibited an excellent sensitivity towards the reduction of iodate, which can be attributed to the electrical conductivity, nanoporous structure of the copolymer composite and an electrostatic interaction between the cationic oxidized (p-doped) copolymer and the anionic iodate. The electrochemical behavior of iodate has been investigated by amperometry and cyclic voltammetry at copolymer modified electrode. Amperometry revealed that there existed a good linear relationship between peak current with the concentration in the range of 50-550 mu M and the detection limit of 0.8 mu M. This composite film was also successfully applied in determination of iodate in urine. (C) 2014 Elsevier B.V. All rights reserved.