2,3,4,4'-Tetrahydroxydeoxybenzoin (THDB) was synthesized and characterized by IR, UV, ¹H NMR, MS and elemental analysis. Single crystals of THDB were determined by X-ray single crystal diffraction. The scavenging effect of THDB on hydroxy radical was detected by fluorescent spectrophotometry. The experimental results show that the crystal (C₁₄H₁₂O₅•2H₂O) belongs to monoclinic space group C2/c with unit cell constants a＝1.4346(5) nm, b＝1.3378(5) nm, c＝1.5709(5) nm, α＝90°, β＝110.823(6)°, γ＝90°, V＝2.8181(16) nm³, Z＝8, D_c＝1.397 g/cm³, μ＝0.113 mm^－1, F(000)＝1248, R＝0.0528, wR＝0.1307. The compound THDB can scavenge hydroxy radical effectively.

Key words: isoflavone, 2,3,4,4'-tetrahydroxydeoxybenzoin, crystal structure, antioxidant