Two hydrates of sodium 5,7-dihydroxy-6,4'-dimethoxyisoflavone-3'-sulfonate (~a(HzO)J(C1,H,306S0~).2HZ0, 1) and nickel 5,7-dihydroxy-6,4'-dimethoxyisoflavone-3'-sulfonate (~i(Hz0)6](C1~H1~0~S03)2.4H~0, 2) were synthesized and characterized by IR, 'H NMR and X-ray diffraction analyses. The hydrate 1 crystallizes in the monoclinic system, space group P2(1) with a=0.8201(9) nm, b=0.8030(8) nm, c=1.5361(16) nm, /7=102.052(12)", V =0.9893(18) nm3, D,= 1.579 g/cm3, Z=2, p=0.252 nm-I, F(000)=488, R=0.0353, wR=0.0873. The hydrate 2 belongs to triclinic system, space group P-1 with a=0.7411(3) nm, b=0.8333(3) nm, c=1.7448(7) nm, a= 86.361(6)", /7=86.389(5)", y=88.999(3)", V=1.0731(7) nm3, D,= 1.587 g/cm3, Z=1, p=0.649 m-', F(OOO)= 534. In the structure of 1, the sodium cation is coordinated by six oxygen atom and two adjacent ones are bridged by three oxygen atoms to form an octahedron chain. The C-H-.n hydrogen bonds exist between two isoflavone molecules in the structure of 2. Meanwhile, hydrogen bonds in two compounds, link themselves to assemble two three-dimensional network structures, respectively.Keywords dimethoxyisoflavone-3'-sulfonate, crystal structure, C-H.. T , hydrogen bond irisolidon, sodium 5,7-dihydroxy-6,4-dirnethoxyisoflavone-3'-sulfonate, nickel 5,7-dihydroxy-6,4'-*