The generation of a new electrocatalytic system for NADH after oxidizing flavin adenine dinucleotide (FAD) is shown. The oxidation is performed in alkaline medium until +1.4 V (Ag/AgCl) at graphite electrodes. The catalytic activity is ascribed to the electrooxidized moiety of FAD and not to quinone surface groups. A comparison between this catalyst and that attributed to poly(FAD) (Karyakin, A. A.; Ivanova Y. N.; Revunova, K. V.; Karyakina, E. E. Anal. Chem. 2004, 76, 2004-2009.) is presented. It is concluded that the surface quinone groups generated during the strong anodization of the electrode in acidic medium at 2-2.5 V and not the poly(FAD) are responsible for the catalytic activity described in the above mentioned work.