The feasibility of using electrodes modified with polyaniline incorporated carbon particles films for improving the precision of coulometric titration is demonstrated. The problem of large deviation produced during determining polyisoprene by coulometric titration with direct titration technique(double Pt electrodes indicating electrode) has been solved. In the titration process, polyisoprene alcohol, an electro-inactive species, is adsorbed on the surface of the bare Pt electrode, which inhibits the electrode reaction of Br - and Br 2. Therefore, when the titration reaches the end-point, the detected current will slowly change with time, which can make the repeatability of end-point poor. The atomic force microscopic images show the morphology of the electrode surface of adsorbing polyisoprene alcohol. The application of the chemically modified electrode instead of the bare Pt electrode to indicating the end-point has been investigated. The results show that the Pt electrode coated with polyaniline incorporated carbon particles films is an excellent indicator electrode. This electrode has advantages that the indicating signals are sharp and repeatable at end-point. The precision and the accuracy of the determination of polyisoprene alcohol are satisfactory. The feasibility of using electrodes modified with polyaniline incorporated carbon particles films for improving the precision of coulometric titration is demonstrated. The problem of large deviation generated during determining polyisoprene by coulometric titration with direct titration technique (double Pt electrodes indicating electrode) has been solved. In the titration process, polyisoprene alcohol, an electro-inactive species, is adsorbed on the surface of the bare Pt electrode, which inhibits the electrode reaction of Br - and Br 2. Thus, when the titration reaches the end-point, the detected current will slowly change with time, which can make the repeatability of end-point poor. The atomic force microscopic images show the morphology of the electrode surface of adsorbing polyisoprene alcohol. The application of the chemically modified electrode instead of the bare Pt electrode to indicating the end-point has been investigated. The results show that the Pt electrode coated This electrode has advantages that the indicating signals are sharp and repeatable at end-point. The precision and the accuracy of the determination of polyisoprene alcohol are satisfactory.