Abstract: Objective To establish a new method for the determination of octylphenol(OP)using modified electrode.Methods c-CNT-chitosan modified electrode was constructed by immobilizing carboxylic carbon nanotubes on the surface of chitosan modified glassy carbon electrode with a self-assembly method.The electrochemical behavior and determination of OP with modified electrode were investigated by cyclic voltammetry and differential pulse voltammetry in pH 6.0 phosphate buffer solution.Results In phosphate buffer solution at pH of 6.0,the calibration curve for OP determination could be obtained with the linear range of 8.33×10^-8-2.0×10^-5 mol/L and the estimated detection limit of 3.67×10^-8 mol/L(S/N=3).The relative standard deviation was 3.6% for ten determinations of 3.0×10^-6 mol/L OP using the same electrode.The recoveries ranged from 92.5%-106.5% for the samples detected.Conclusion The method is simple and sensivite and could be applied to the determination of OP in samples.