A monoclinic BiVO 4 ( mBiVO 4) film composed of nanoparticles with a size of 100 nm was prepared via a citrate-precursor chemical route. The BiVO 4 film was characterized by X-ray diffraction, scanning electron microscopy and absorption spectra. It was found that the mBiVO 4 film showed a photocatalytic activity of Acid Orange 7 (AO7) degradation in aqueous solution under visible-light irradiation ( λ > 400 nm). The degradation efficiency was 78.9% in 3 h and basically remained constant in 10 repeated batch runs. The results demonstrated that the mBiVO 4 film had a high photocatalytic activity under visible light and good durability in repeated use.