The electrochemical redox reaction of hydroquinone (HQ) and catechol (CC)was investigated with poly-(p-aminobenzoic acid) modified glassy-carbon electrode (poly-p-ABA/GCE) via cyclic voltammetry (CV) and differential Pulse voltammetry (DPV). The Poly-p-ABA/GCE has shown an excellent electrocatalytic activity for HQ and CC in 0.1 ml L-1 phosphate buffer solution (PBS). The oxidation and reduction separation (Delta E) has been decreased from 353 to 32 mV for HQ and from 228 to 33 mV vs. SCE for CC at the bare GCE and poly-p-ABA/GCE respectively. DPV curves show that the oxidation potential of HQ and CC has a separation about 105 mV at the poly-p-ABA/GCE. Moreover, the oxidation current of HQ and CC has been enhanced two and four times respectively at the modified electrode. Using DPV method, a highly selective and simultaneous determination of HQ and CC has been explored at the poly-p-ABA/GCE. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 2881-2886, 2009