The pristine fluorine-doped SnO 2 (abbreviated as FTO) inverse opal (IO) was developed using a 410 nm polystyrene bead template. The nanolayered copper tungsten oxide (CuWO 4) was decorated on the FTO IO film using a facile electrochemical deposition, subsequently followed by annealing at 500 o C for 90 min. The morphologies, crystalline structure, optical properties and photoelectrochemical characteristics of the FTO and CuWO 4-decorated FTO (briefly denoted as FTO/ CuWO 4) IO film were investigated by field emission scanning electron microscopy, X-ray diffraction, UV-vis spectroscopy and electrochemical impedance spectroscopy, showing FTO IO in the hexagonally closed-pack arrangement with a pore diameter and wall thickness of about 300 nm and 20 nm, respectively. Above this film, the CuWO 4 was electrodeposited by controlling the cycling number in cyclic voltammetry, suggesting that the CuWO 4 formed during 4 cycles (abbreviated as CuWO 4 (4 cycles)) on FTO IO film exhibited partial distribution of CuWO 4 nanoparticles. Additional distribution of CuWO 4 nanoparticles was observed in the case of FTO/CuWO 4 (8 cycles) IO film. The CuWO 4 layer exhibits triclinic structure with an indirect band gap of approximately 2.5 eV and shows the enhanced visible light absorption. The photoelectrochemical (PEC) behavior was evaluated in the 0.5 M Na 2 SO 4 solution under solar illumination, suggesting that the FTO/CuWO 4 (4 cycles) IO films exhibit a photocurrent density (J s c

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