A sensitive, selective and reproducible electrochemical method was developed for the electroanalysis of important phenolic isomers such as catechol (CC) and hydroquinone (HQ) using poly(brilliant blue) modified carbon paste electrode. The modified electrode shows excellent electrocatalytic activity towards the oxidation of CC and HQ in phosphate buffer solution of pH 7.4 by cyclic voltammetric (CV) and differential pulse voltammetric (DPV) techniques. The lower limit of detection of CC and HQ was 68.1 nM and 46.4 nM respectively. The peak to peak separation of CC and HQ was about 0.107 V by both CV and DPV techniques. This work provides a simple and easy approach for the simultaneous analysis of CC and HQ. (C) 2015 Elsevier B.V. All rights reserved.