In this study, the photo-functional property of iron oxyhydroxide was examined. The study assessed the hydrogen production resulting from UV irradiation of iron oxyhydroxide. In theory, iron oxyhydroxide absorbs the visible light; therefore, it should not produce hydrogen under UV light. However, we succeeded in producing hydrogen under UV irradiation without an applied voltage or any other condition. The amount of hydrogen produced was affected by the presence of oxygen and the solution pH. In addition, the shape and crystallinity of iron oxyhydroxide were not changed after the reaction for hydrogen production. These results demonstrated the circular reaction of iron oxyhydroxide related with the Photo-Fenton reaction. (C) 2020 Elsevier Ltd. All rights reserved.