In this study, photoelectrochemical properties of a double-layered n-type GaN in NaOH aqueous solution were investigated. Several electrical properties such as impedance, photocurrent-voltage property, and photocurrent-time relationship were examined for comparison. After the measurement the electrical properties, the surface of GaN photoelectrodes were observed by field emission scanning electron microscope to confirm the electrolytic corrosion. The results of this study indicate that the double-layered n-GaN electrode increased the photocurrent density compared to the single-layered electrode. Moreover, the surface of the double-layered n-GaN electrode was more stable than that of the single-layered n-GaN, indicating that surface layer preserved the lower layer from photocorrosion, and also its depletion length was enough to help the movement of carriers. These results show that the double-layered n-GaN electrode has more advantages than the single-layered n-GaN electrode. (C) 2014 The Electrochemical Society. All rights reserved.