L-Histidine was attached to a silver electrode by a covalent bond. Cyclic voltammetric experiments demonstrated that the modified electrode can catalyze the reduction of NAD(+) to enzymatically active NADH at a substantially lower overpotential (i.e., -0.72 V vs. SCE). The electrochemical reduction mechanism was investigated by in situ spectroelectrochemistry. It is possible to envisage the formation of NADH through direct electron transfer. The modified electrode could be useful in enzymatic synthesis processes and in dehydrogenase-based biosensors.