The kinetics of Prussian blue (PB) film itself during the redox process and of the catalytic oxidation of ascorbic acid (AH2) on it have been studied in detail. The charge transfer diffusion coefficient Dct in PB film is determine as 2.62 ?10-10 cm2.s-1, using potential-step chronoamperometry, chronocoulometry and constant- chronopotentiometry. The rate constant of the cross-exchange reaction between AH2 in solution and the active centers in PB film is measured in rotating disk electrode as 1.23 ?108 cm3.mol-1.s-2. The catalytic reaction occurs only at the outer most part of the PB film and is first order to the bulk concentration of AH2. The overall process can be limited by mass transfer in solution, by cross-exchange reaction at the film-soln. interface, by charge transfer within the film or by some kind of combination of them, with four kinetic subcases experimental observed and analyzed.

Key words: REACTION KINETICS, VITAMIN C, MEMBRANE ELECTRODES, CHEMICAL MODIFIED ELECTRODE, ELECTRO-CATALYSIS, CATALYTIC OXIDATION, ELECTROOXIDATION, PRUSSIAN BLUE