The coenzyme dihydronicotinamide adenine dinucleotide (NADH) can be directly oxidized at similar to 0.23 V at a bare silver electrode. Not only is the overpotential lower than that at the commonly used carbon or platinum electrodes, but the coenzyme gives a cathodic peak at. similar to 0.12 V which can be assigned to the reduction of the oxidized form. Since no mediator for the redox reaction of NAD(+)/NADH is present at the silver electrode surface, the working electrode is obviously stable and the reaction reported here is useful for electrochemical studies of the nicotinamide coenzyme.