The mediated oxidation of N-acetyl cysteine (NAC) and glutathione (GL) at the palladized aluminum electrode modified by Prussian blue film (PB/Pd-Al) is described. The catalytic activity of PB/Pd-Al was explored in terms of Fe-III[Fe-III(CN)(6)]/Fe-III[Fe-II(CN)(6)](1-) system by taking advantage of the metallic palladium layer inserted between PB film and Al, as an electron-transfer bridge. The best mediated oxidation of NAC and GL on the PB/Pd-Al electrode was achieved in 0.5 M KNO3 + 0.2 M potassium acetate of pH 2. The mechanism and kinetics of the catalytic oxidation reactions of the both compounds were monitored by cyclic voltammetry and chronoamperometry. The charge transfer-rate limiting step as well as overall oxidation reaction of NAC or GL is found to be a one-electron abstraction. The values of transfer coefficients alpha, catalytic rate constant k and diffusion coefficient D are 0.5, 3.2 x 10(2) M-1 s(-1) and 2.45 x 10(-5) cm(2) s(-1) for NAC and 0.5, 2.1 x 10(2) M-1 s(-1) and 3.7 x 10(-5) cm(2) s(-1) for GL, respectively. The modifying layers on the Pd-Al substrate have reproducible behavior and a high level of stability in the electrolyte solutions. The modified electrode is exploited for hydrodynamic amperometry of NAC and GL The amperometric calibration graph is linear in concentration ranges 2 x 10(-6)-40 x 10(-6) for NAC and 5 x 10(-7)-18 x 10(-6) M for GL and the detection limits are 5.4 x 10(-7) and 4.6 x 10(-7) M, respectively. (C) 2008 Elsevier B.V. All rights reserved.