A water-soluble two-arm fullerene-containing poly(ethylene oxide) (PEO) was synthesized through isocyanate-hydroxy condensation reaction with fullerenol as a molecular core and characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry, and matrix-assisted laser desorption ionization time of flight mass spectrometry. The aggregation behavior of the resulting amphiphilic polymer in water, THF, and DMF, was studied by gel permeation chromatography, laser light scattering, and transmission electron microscopy. The polymer forms spherical aggregates with an aggregation number around 540-1020. (C) 2003 Elsevier Science Ltd. All rights reserved.