Ni,Fe-based (oxy) hydroxides have been one of the most active catalysts for the oxygen evolution reaction. In this article, reduced graphene oxide supported Ni doped FeOOH (RGO/Ni:FeOOH) was prepared for electrochemical and photoelectrochemical (PEC) water oxidation. The RGO/Ni: FeOOH exhibited a lower over-potential (260 mV at 10 mA cm(-2)) and smaller Tafel slope (32.3 mV dec(-1)) than that of the FeOOH and Ni: FeOOH. Such significant enhancement is attributed to Ni doping and RGO, which reduce the over-potential, improve the conductivity and enlarge surface areas. Besides, RGO/Ni: FeOOH decorated the TiO2 nanorods (NRs) was also fabricated for photoelectrochemical (PEC) water oxidation, which exhibited a higher photocurrent density and lower onset potential than that of TiO2 NRs the bare under illumination due to the synergistic effect of RGO and Ni: FeOOH. These results demonstrate the RGO/Ni: FeOOH has great promising as a co-catalyst to improve the PEC performance. (C) 2017 Elsevier B.V. All rights reserved.