Abstract: Nanoparticles Bi₂O3 have been prepared by using the ammo nia precipitation and polyol mediated methods. XRD, BET and XPS were used to characterize the nanoparticles. The photocatalytic oxidation of toluene was used as model reaction to measure the photocatalytic a ctivity of Bi₂O_{3 nanoparticles. The results show that the prepared crystals possess a tetragonal structure . The electron combining energy of Bi2O3 nanoparticles inc reases as the calcinin g temperature increases, resulting in the photocatalytic activity for toluene degradation to increase. The photocatalytic activity of Bi2O3 nanoparticles produced by the polyol mediated method　 is higher than that of Bi2O3 nanoparticles produced by 　the ammonia precipitation.}

Key words: preparation, Bi_2O3, characterization, photocatalytic deg radation