Abstract. The results of photocatalytic activity of tungsten oxide in visible light are analyzed. It was shown that tungsten oxide has photocatalytic activity under the action of visible light in the photodegradation of the dye methylene blue. It was determined that the concentration of 15 mg/L provides the highest rate of photodecomposition of methylene blue. The optimum temperature for the process was determined. The process of methylene blue decomposition is most effective at 25 °С.