C60 composites with poly(ethylene oxide) and poly(ethylene glycol) in which C60 occurs in the bound state were prepared by the thermal treatment of a molecular-dispersed fullerene C60-polymer mixture at temperatures that are 30-60°C higher than the melting temperature of the polymers. PEO-C60 composites with different molecular masses and preset contents of C60 combine hydrophilicity of the polymer and hydrophobicity of C60. The hydrodynamic and electrooptical properties of the composites in benzene solution significantly differ from those of the starting PEO samples subjected to the same treatment procedure. The experimental results obtained are compared with the data available for other polymers and are explained by a change in the mechanism of thermal degradation of macromolecules in the presence of C60 dispersed in a polymer matrix.