Cyclic voltammetry was used to investigate the electrochemical behavior of ascorbic acid (AA) at the poly(glutamic acid) chemically modified electrode (PME) in phosphate buffer solution. A decrease of 400 mV in overpotential was obtained. The number of electrons involved in the reaction (two electrons) and the catalytic rate constant (1.2 × l0 4 M −1s −1) were determined using a rotating electrode. Hydrodynamic voltammetric experiments were performed to characterize the electrode as an amperometric sensor for the determination of AA. At 0.3 V, in pH 5.0 PBS, the detection limit was 4.0 × 10 −8 M when S N=3 . The catalytic effect on the catalytic oxidation of AA resulted in the separation of the overlapping voltammograms of AA and dopamine at the glassy carbon electrode in a mixture.