γ, Irradiated rutin and baicalin ethanol solutions saturated with air were eluted through alumina columns and the ,G, values of hydrogen peroxide generated in the solutions were measured. Different results from former works were obtained and the reasons of the difference were discussed. A precise method was established as follows : hydrogen peroxide should be separated from flavonoids by passing the flavonoids ethanol solutions through alumina columns before the measurement and the amount of hydrogen peroxide generated from self—oxidation of the flavonoids should be deducted. Under a dose rate of 6.93Gy min,-1, the ,G, values of hydrogen peroxide in ,γ, irradiated rutin and baicalin ethanol solutions saturated with air were determined to be 5.5±0.2 and 7.3±0.2, separately. After irradiation of rutin— and baicalin—O,2,—ethanol solutions, the ,G, values of hydrogen peroxide were increased comparing with that of pure ethanol—O,2, solution.