The nitration of naphthalene (NapH) at a Pt electrode in acetonitrile (ACN) in the presence of excess NaNO2 has been studied in detail. First, the electrochemical behavior of the reactants NapH and NaNO2 was investigated by cyclic voltammetry to determine the electrolysis conditions. When both substrates are in the solution, two well-defined peaks are observed which correspond to the oxidation of NO2- and NapH. The peak current of NapH is not linear with the concentration of NapH, indicating that either the NO2- ion or its oxidation product interacts with NapH(.+), changing its route of degradation. This effect increases with increasing NapH/NO2- ratio. These studies showed that the nitration reaction between NapH(.+) and NO2 is fast and competes with another coupling reaction, the dimerization of NapH(.+) to give binaphthyl. Controlled-potential electrolysis, with the concentration of NaNO2 kept constant, gave high yields of nitration products. The 1-nitronaphthalene/2-nitronaphthalene ratio was always greater than 50 at the end of the electrolysis (i.e. less than 2 h). These results indicate that the nitro products are obtained for the selective reaction between NO2 and NapH(.+). A reaction mechanism is proposed which accounts for the yields and the competitive reactions under these conditions.