Gold nanoparticles were embedded into an electroactive polymer layer to modify the glassy carbon (GC) electrode and to fabricate a novel catalyst electrode. Cyclic voltammetry was performed to form the electroactive polymer, poly(aminothiophenol), PATP and deposit the Au-0 nanoparticles, simultaneously. 4-Aminothiophenol (ATP) was converted into an inclusion complex with (3-cyclodextrin and used to form the electroactive layer on the surface of GC electrode. Au nanoparticles were incorporated into film of PATP simultaneously by the electrolysis of a solution of HAuCl4. Thus, newer catalyst electrode, PATP-Au-nano, was fabricated. The scanning probe microscopic image of PATP-Au-nano indicates the presence of uniformly distributed Au nanoparticles of the sizes similar to 10 nm. Electroactivity of PATP-Au-nano for reduction of dioxygen (O-2) was evaluated in O-2 saturated solution. Cyclic voltammetry was used to demonstrate the enhanced electrocatalytic activity of the PATP-Au-nano. A reduction peak at similar to 430 mV with an enhanced peak current was observed for the oxygen reduction reaction (ORR) in O-2 saturated 0.5 M sulfuric acid solution. A more positive onset potential and higher catalytic current for ORR are the striking features of PATP-Au-nano catalyst. Double potential chronoamperometry, rotating disc (RDE) and rotating ring-disk electrode (RRDE) experiments were carried out to investigate the kinetic parameters of ORR on this electrode. Results from RDE and RRDE voltammetry experiments demonstrate that ORR on the PATP-Au-nano is a four electron and diffusion controlled process with a catalytic rate constant of 3.65 x 10(3) M-1 s(-1) and a diffusion coefficient of 7.82 x 10(-5) cm(2) s(-1). (c) 2006 Elsevier B.V. All rights reserved.