An N-doped graphene electrode has been prepared by cyclic voltammetric method in 5.0M of HNO3 solution on a graphite-based electrode at room temperature. The modification of the electrode surface with different types of N-containing groups, such as nitro groups, pyrrolic N, and pyridinic N, has been controlled by changing the scanned potential ranges. The formation of an N-doped graphene electrode has been confirmed by scanning electron microscopic, atomic force microscopic, X-ray photoelectron, and Raman spectroscopic methods. The prepared N-doped graphene-modified electrodes have been used in positive electrolyte of a vanadium-based redox flow battery. As positive electrodes, the electrochemically modified electrodes prepared in 5.0M of HNO3 solution -1.0 to (+1.9) and -0.7 to (+1.9) V had more than 140 and 120mA/cm(2) anodic and cathodic peak currents, respectively, in vanadium redox battery. This fast, low-cost, and environmentally friendly method can be used in many application areas, such as optical devices, (bio)sensors, energy storage materials, and electronic devices.