Graphite electrodes chemically modified with Prussian Blue (G/PB) were obtained by spreading, on the electrode surface, appropriate volumes of 100 mM K-3[Fe(CN)(6)] and 100 mM FeCl3 solutions, both containing 10 mM HCl. In order to improve the electrochemical response stability, the potential of G/PB electrodes was cycled (in the domain where PB exhibits electrochemical activity) in 0.1 M KCl solution (G/PB-K), as well as in 2 mM RhCl3 solution, containing 0.05 M KCl (G/PB-Rh). Compared with G/PB-K, the G/PB-Rh modified electrodes showed: (i) higher relative stability of the PB electrochemical response; (ii) better analytical parameters for H2O2 amperometric detection; (iii) slightly lower rate constant corresponding to the second order electrocatalytic reaction for H2O2 amperometric detection; (iv) an electrocatalytic activity not affected by the H2O2 concentration.