The surface of glassy carbon electrode (GCE) was modified by electrochemical pre-treatment method and has been employed for the cyclic voltammetric determination of catechol (CC) in the presence of resorcinol (RS) in 0.2 M phosphate buffer solution (pH 7.4) with scan rate 50 my s(-1). The electrochemical oxidation of catechol (CC) and resorcinol (RS) was investigated by both cyclic voltammetry (CV) and differential pulse voltammetric (DPV) methods at pre-treated glassy carbon electrode (PGCE). The modified electrode (PGCE) showed excellent electrocatalytic activity towards CC and RS determination. The parameters like effect of scan rate, concentration, and interference study were investigated at PGCE. The electrode process was found to be adsorption-controlled at PGCE. Furthermore, the modified electrode exhibited good limit of detection (CC = 0.94 mu M, RS = 0.72 mu M) and limit of quantification (CC = 31.5 mu M, RS = 24.1 mu M) for CC and RS. Hence, the pre-treated glassy carbon electrode shows good electrocatalytic properties and can be applied for the determination of CC and RS individually and simultaneously.