Single-C-60-end-capped poly(ethylene oxide) (FPEO) forms a stoichiometric inclusion complex with alpha-cyclodextrin in high yield. The complex was characterized by XRD, C-13 CP/MAS NMR, H-1 NMR, DSC, and TGA. The incorporation Of C-60 results in no apparent change in the crystal structure. No complex forms between FPEO and P-cyclodextrin. gamma-Cyclodextrin (gamma-CD) and FPEO form a thermoreversible gel in aqueous solution instead of a stoichiometric crystalline complex, whereas uncapped polymers form crystalline inclusion complexes with gamma-CD in high yields. Interestingly, in a gamma-CD/FPEO/PEO aqueous solution, two PEO chains are able to "recognize" each other and thread through the gamma-CD cavity to form a gamma-CD/PEO inclusion complex.