A poly-amidosulfonic acid and multi-wall carbon nanotubes composite (PASA/MWNTs) modified electrode has been constructed by electropolymerization on glassy carbon electrode (GCE). The electrochemical behaviors of hydroquinone (HQ) and catechol (CC) were investigated using cyclic and differential pulse voltammetries (DPVs) at the prepared electrode. Separation of the reductive peak potentials for HQ and CC was about 120 mV in pH 6.0 phosphate buffer solution (PBS), which makes it suitable for simultaneous determination of these compounds. In the presence of 1.0 x 10(-4)mol L(-1) isomer, the reductive peak currents of DPV are proportional to the concentration of HQ in the range of 6.0 x 10(-6) to 4.0 x 10(-4)mol L(-1), and to that of CC in the range of 6.0 x 10(-6) to 7.0 x 10(-4)mol L(-1). When simultaneously changing the concentration of both HQ and CC, the linear concentration range of HQ (or CC) is 6.0 x 10(-6) to 1.0 x 10(-4)mol L(-1) (or 6.0 x 10(-6) to 1.8 x 10(-4)mol L(-1)), and the corresponding detection limits are 1.0 x 10(-6)mol L(-1). The proposed method has been applied to simultaneous determination of HQ and catechol in water sample, and the results are satisfactory.