Solar-to-hydrogen conversion from water splitting have received a great of interest because it can alleviate the serious environmental pollution and energy crisis. The KNbO(3)photocatalyst with high conduction band and excellent anticorrosion has been reported for water splitting, but the large band gap and low separation efficiency of electron-hole pairs restrict its photocatalytic activity. In this work, the CoO/KNbO(3)p-n heterojunction photocatalysts were prepared via a hydrothermal and calcination method, which exhibits excellent photocatalytic for H(2)production with high rates at 144.36 mu mol h(-1) g(-1)under simulated sunlight and 76.78 mu mol h(-1) g(-1)under visible light irradiation (lambda > 420 nm). The enhanced H(2)production was ascribed to the improvement of visible light absorption and the efficient charge separation after the formation of CoO/KNbO(3)p-n heterojunction, which was evidenced by the UV-vis diffuse spectra and transient photocurrent. Finally, a possible mechanism was proposed for the CoO/KNbO(3)p-n heterojunction photocatalysts toward the photocatalytic activity of H(2)production. This kind of CoO/KNbO(3)p-n heterojunction photocatalysts can provide a reference for developing high-efficiency KNbO3-based photocatalysts.