The fractional determination of ascorbic acid 2-sulfate (AsS), ascorbic acid (AsA) and dehydroascorbic acid (DAsA) was examined by hydrazine method. By using bromine as oxidizing agent of AsS on hydrazine method, the formation of DAsA and inorganic sulfate was confirmed quantitatively, but stabled to 2,6-dichlorophenolindophenol (DCIP). When each value by hydrazine method from tissues extract oxidized with DCIP and bromine were numerically almost equal, in these tissues, determination of added or intubated AsS in the tissues were following. Half volume of AsS solution extracted with metaphosphoric acid solution was oxidized with bromine at 37℃ for 10 min. Bromine was expelled by N_2 gas after reaction. The remainder extract was oxidized with DCIP at room temperature for 5 min. Both oxidized solutions were treated by hydrazine method and determined photometrically at 530 nm, respectively. The AsS levels in AsS treated tissues were obtained from following equation, AsS=bromine value (AsS+AsA+DAsA)-DCIP value (AsA+DAsA). The detective percent of additional AsS in tissues were 90〜100 in this method.