In recent years, graphene oxide (GO) has attracted a lot of attention as materials of an electrode for rechargeable batteries and supercapacitors. During the processes of GO conversion from a graphite, various oxygen containing functional groups and impurities such as sulfuric acid are engaged into the GO structure and GO flake, respectively, and they deteriorate the electrical properties and dispersivity of GO. In this study, we carried out washing process of GO flake using a centrifuge. Through the washing process, the remaining acid and impurities almost disappeared and the dispersivity of GO in DI water increased greatly. By using this GO dispersion, freestanding GO films of about 15μm thickness were prepared. Since these GO films have poor electrical conductivity and small specific surface area, they should be reduced in order to recover graphene like properties before being used as an electrode. For the reduction process, we employed an intense pulsed light (IPL) of Xe flash lamp and introduced a shadow mask between IPL and GO film during irradiation and the obtained photoreduced GO film showed improved properties compared to the photoreduced one without shadow mask. The photoreduced GO films were analyzed by Raman and infrared spectroscopy, and the electrochemical properties of supercapacitors with the GO electrodes were evaluated by cyclic voltammetry and impedance spectroscopy. The specific capacitance over 170 F/g was achieved.