Aqueous solutions of alpha-cyclodextrin (alpha-CD), a cyclic oligomer formed by six glucose units, complex spontaneously with poly(ethylene oxide), PEO, and several molecules of alpha-CD thread onto the host polymer chain. A new nanocomposite has been synthesized by the complexation of PEO physically adsorbed on the surface of colloidal silica with alpha-CD. The PEO monomers adsorbed on the silica surface were displaced by changing the degree of complexation and the MW of the polymer. As the inclusion of a-CD can only start, from the extremity of the PEO chain, the fraction and length of the tails can be studied by changing, the number of alpha-CD molecules threaded. Adsorbed PEO of 1000 molecular weight can be completely included in the cavities of alpha-CD molecules, resulting in a full displacement of the adsorbed polymer. However, for PEO 6k and 20k, the complexation of the chain is partial, that is, some nonincluded EO units remain adsorbed on the silica surface. In these cases, a gel containing silica was formed in the hydxogel network. The effect of silica on the yield of the complexation was also studied. The solid-state complexes formed by [silica-PEO-alpha-CD] were characterized by FTIR, SEM, and X-ray diffraction.191148124816