In this study, BaTaO2N was synthesized as a visible-light-active water-splitting photocatalyst via the flux method using NaNH2. The synthesis was conducted at 493 K, which is approximately 500K lower than the temperature used in previous methods. The products were characterized using X-ray diffraction, field-emission scanning electron microscopy, and ultraviolet-visible (UV-vis) spectrophotometry. Moreover, the photocatalytic activity of the products was measured. The products exhibited photocatalytic activity for hydrogen and oxygen evolution under visible-light irradiation.