A simple and sensitive electroanalytical method was developed to determine the Endocrine Disrupting chemical 4-tert-octylphenol on clay modified carbon paste electrode (Clay/CPE). The electrochemical response of the proposed electrode was studied by means of cyclic and square wave voltammetry. The structural morphology of the modified electrode was characterized by SEM/EDX and XRD techniques. It has been found that the oxidation of 4-tert-octylphenol on the clay/CPE displayed a well-defined oxidation peak. Factors influencing the detection processes were optimized. 4-tert-octylphenoloxidation occurred through a surface process involving its adsorption on the clay/CPE. Under these optimal conditions, a linear relation between concentrations of 4-tert-octylphenoland current response was obtained over the range of 7.26 x 10(-6) to 3.87 x 10(-7) with a detection limit and a quantification limit of 9.2 x 10(-7) M and 3.06 x 10(-6) M, respectively. The correlation coefficient is 0.9963. The modified electrode showed suitable sensitivity, high stability and an accurate detection of 4-tert-octylphenol. The modified electrode also relevant suitable selectivity for various phenolic estrogenic compounds such as 4-Nonylphenol and Bisphenol A. (C) 2014 The Electrochemical Society. All rights reserved.