The electrocatalytic ability of the modified electrodes for the reduction of dioxygen to hydrogen peroxide was investigated by using cyclic voltammetry and chronocoulometry techniques at poly(p-aminobenzene sulfonic acid) (PABS)-modified glassy carbon electrodes. The electrochemical reduction of oxygen (O-2) has been studied in pH 7.0 buffer solution by using PABS-modified glassy carbon rotating ring disk electrode (RRDE). The PABS-modified glassy carbon (GC) electrode (GC/PABS) showed excellent electrocatalytic activity for oxygen and hydrogen peroxide (H2O2) reduction reactions. The RRDE data indicated that the reduction of oxygen on GC/PABS electrodes proceeds by a two-electron pathway in aqueous buffer solution (pH 7.0). In addition, PABS-coated GC electrode was successfully utilized as an enzyme-less amperometric sensor for the detection of hydrogen peroxide (H2O2) in the range from 50 to 550 mu M with detection limit of (S/N=3) 10 mu M. (c) 2007 Elsevier B.V. All rights reserved.