An inclusion complex β-cyclodextrin-salicylic acid (β-CD-sal) [(C₄₂H₇₀O₃₅)₂•(C₇H₆O₃)₂•(H₂O)₂₄] was prepared between β-cyclodextrin and salicylic acid, and its structure was investigated by X-ray single crystal diffrac-tion, NMR and elemental analysis. The crystallographic study has shown that the inclusion complex belongs to the monoclinic system (space group: C₂) with unit cell dimensions a＝1.9269(5) nm, b＝2.4395(7) nm, c＝1.6095(4) nm, β＝107.816(5)°, V＝7.203(3) nm³, Z＝4, D_c＝1.373 g•cm^－3, F(000)＝3176, R[I＞2σ(I)]＝0.0971. The results show that β-cyclodextrin and salicylic acid form 2∶2 inclusion complex in which the β-cyclodextrins exist as a head-to-head dimer by means of extensive hydrogen bonding across the secondary hydroxyl groups and the salicylic acids are included in the dimer in different mode, i. e. one salicylic acid molecule is included in the cavity of the β-cyclodextrin, and the other is sandwiched in the in-terface of the dimer.

Key words: inclusion complex, crystal structure, cyclodextrin, supramolecule