Abstract: Co₃O₄/Bi₂O₃ nanoparticles were prepared by the microemulsion chemical method. The structure of the asprepared Co₃O₄/Bi₂O₃ nanoparticles was characterized by means of TG-DAT, XRD, XPS and FT-IR absorption spectra. The photocatalytic oxidation reaction of toluene was used as model reaction to measure the photocatalytic activity of Co₃O₄/Bi₂O₃. The results show that the photocatalytic activity of the Co₃O₄/Bi₂O₃ particles is higher than that of pure Bi₂O₃．The increasing level of photocatalytic activity is related to the ratio of n(Co) ∶n(Bi) and the best ratio is 0.02 ∶1．　With the calcining temperature increasing, the photocatalytic activity is increased, and the best calcining temperature is 750 ℃．

Key words: Co₃O₄/Bi₂O₃, toluene, photocatalytic