A series of organic-inorganic star-shaped poly(ethylene glycol)s from octa-functional silsesquioxane (POSS) cores were synthesized by allylation and hydrosilylation, and they were found to form crystalline inclusion complexes with alpha,gamma-cyclodextrins. The results from X-ray diffraction, cross-polarity/magic-angle-spinning C-13 NMR, differential scanning calorimetry, and Fourier transform infrared suggested that a channel-type structure was established in the inclusion complexes. The characterization results also revealed that the segments of poly(ethylene glycol) arms near the POSS cores were uncovered by the cyclodextrins, whereas the cyclodextrins were closely packed along the remaining portion of the poly(ethylene glycol) arms. Molecular dynamic simulation in a Dreiding force field with Cerius(2) software gave comparable results. (C) 2004 Wiley Periodicals, Inc.