An activated carbon modified carbon paste electrode (AC/CPE) was fabricated, and the electrochemical oxidation of resorcinol (RS) was studied in phosphate buffer solution. The results revealed that the activated carbon has a catalytic effect on the oxidation current of RS in buffered solution relative to an unmodified carbon paste electrode. The oxidation mechanism was studied using cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS). The results demonstrated that the oxidation of RS at this AC/CPE electrode was irreversible and co-contribution of adsorption and diffusion. Under the optimal chemical and DPV parameters, the anodic peak current showed a linear relation versus RS concentration in the range from 1.0 × 10 –7 to 1.0 × 10 –4  mol L −1 with detection limit of 3.5 × 10 –8  mol L −1 (3Sb/m). Moreover, the modified electrode demonstrated good repeatability (RSD = 3.12%, n = 8), long-term stability and excellent anti-interference property by peaks separation. This method has been applied to the determination of RS in tap water and commercial hair color samples. The obtained results are similar to those obtained using a high-performance liquid chromatography method (at 95% confidence level). Graphic Abstract