A new method was developed to cross-link water-soluble unsaturated polyester resins prepared from maleic anhydride and poly(ethylene glycol) in water as the solvent. Crosslinking was carried out with various molar ratios of the host-guest complex consisting of styrene as the guest and methylated beta-cyclodextrin as the host. Polymerizations were performed in water with K2S2O8/Na2S2O2 as free radial initiator at 25degreesC. Thermal properties of the networks obtained depend on the amount of styrene incorporated into the polymer.