Abstract: A yellow complex is formed from bismuth and thiourea in hydrochloric acid under the heated condition of 55 ℃. Thus a new method is set up to compare the solubilities of bismuth，bismuth oxide，and bismuth sulfide in hydrochloric acid-thiourea by using spectrophotometry.Effects of factors，such as reaction medium，reagent concentration，heating time，heating temperature，and oscillation speed，were studied respectively.Under the optimum experimental conditions，mass concentration of the solution is in line with Beer′s law，when it is within the range of 0.04～0.24 mg/mL.The correlation coefficient（R） is 0.999 9.The detection limit is 1.05×10^-2 μg/mL.The standard deviation is 0.003 5.The relative standard deviation（RSD） is 2.42%.The molar absorption coefficient is 1.515×10⁵ L/（mol·cm）.The recovery rate of standard addition is at 96.7%~98.8%. Experimental result showed that the solubilities of bismuth，bismuth oxide，and bismuth sulfide in hydrochloric acid-thiourea is in order by size as following：Bi>Bi₂O₃>Bi₂S₃.

Key words: bismuth, bismuth oxide, bismuth sulfide, thiourea, spectrophotometry