[Display omitted] • The Ni-doped WO 3 nanorod films were fabricated by reactive magnetron co-sputtering with GLAD technique. • GIXRD investigation revealed crystalline of annealed Ni-doped WO 3 nanorod film at 500 °C. • The local structural transformation was studied by a combination of XAS and DFT calculation. • Annealed Ni doped WO 3 nanorod photoanode at 400 °C presents an improving. • PEC performance. Ni-doped WO 3 nanorod films were fabricated via a reactive magnetron cosputtering with a glancing angle deposition technique. The crystal structure and surface morphology were observed using grazing incident X-ray diffraction and field emission Scanning Electron Microscopy, respectively. The chemical compositions and oxidation state of each element were investigated by X-ray photoemission spectroscopy. The local structure and phase evolution were investigated via X-ray absorption spectroscopy. The local structure of Ni atoms in WO 3 nanorod films is characterized as a NiWO 4 nanocluster in the WO 3 matrix, which is supported by calculated spectra. The phase information obtained after annealing demonstrates that short-length order in amorphous transitions to crystallinity. The phase information of the local structures were acquired and discussed as well as the effect on the annealing process. The coupling of amorphous WO 3 , crystalline WO 3 , and amorphous NiWO 4 exhibits high photoelectrochemical activity of the sample annealed at 400 °C, which was observed with a large current density (2.35 μA/cm2) at 1.20 V vs. Ag/AgCl under visible light irradiation, which is greater than that of the unmodified WO 3 photoelectrode (1.38 μA/cm2). [ABSTRACT FROM AUTHOR]