A ruthenium complex containing phenanthroline quinone, [Ru(pdon)(2)(aphen)](ClO4)(2) (pdon = 1,10-phenanthroline-5,6dione, aphen = 5-amino- 1, 10-phenanthroline) (1), was prepared as an electrocatalytic adsorbate on a gold electrode. Immobilization of I on the gold electrode was confirmed by surface enhanced resonance Raman spectroscopy. The rate constant k(s) was calculated as 10s(-1) at pH 7.0. The electrocatalytic oxidation of NADH using this modified electrode was investigated.