A sensitive and selective electrochemical sensor for catechol (CC) using a multi-walled carbon nanotubes-poly(1,5-diaminonaphthalene) composite modified glassy carbon electrode (MWCNTs/p-DAN/GCE) is reported. The surface features of the modified electrodes were characterized by a scanning electron microscope (SEM), and an energy-dispersive X-ray spectrometer (EDX). The electrochemical behavior was investigated using cyclic voltammetry (CV). The cyclic voltammogram of the modified electrode is characterized by a remarkable increase in the redox peak currents for CC, which indicates that MWCNTs/p-DAN film enhances significantly the electrocatalytic response toward CC. The effects of different parameters, such as pH, accumulation time, amount of MWCNTs, and scan rate on the response of the developed sensor were investigated. The analytical performances were also investigated using differential pulse voltammetry (DPV). The optimized MWCNTs/p-DAN/GCE based CC sensor exhibited a linear response over a range of 2.0 x 10(-8) to 1.3 x 10(-4) M with a lower limit of detection (LOD) of 1.0 x 10(-8) M (S/N = 3). Moreover, the developed CC sensor is characterized by high sensitivity, excellent repeatability, and excellent selectivity. The proposed sensor showed high selectivity for catechol relative to most potential interferents particularly hydroquinone (HQ) and resorcinol (RC), typical interfering agents. The developed sensor was successfully applied for the determination of CC in real water samples with satisfactory recovery results. (C) 2019 The Electrochemical Society.