Different generations of new hyperbranched polyester polyols were synthesized by the polycondensation of stoichiometric amounts of the monomer 2,2-bis (hydroxymethyl) propionic acid (bisMPA) corresponding to each generation with one mole of 1,3,5-tris(2-hydroxyethyl) cyanuric acid (THECA) as a trifunctional core. The monomer to core ratio was varied between 3 and 45. The degree of branching (DB) was found to be 0.45 according to the method described by Frechet and 0.35 according to the definition introduced by Frey et al. and independent of the stoichiometric ratio between core molecule and repeating monomer. The molecular weights, calculated from H-1 NMR spectra, increase on going from G1 to G4 and represent 97, 90, 72, and 58% from their theoretical molar masses, respectively. In view of the obtained results, it may be argued that the higher generations of the hyperbranched polyesters possess actually lower molecular weights and hydroxyl functionality than their theoretical ones due to some side reactions, e.g., cyclization and or self-condensation of bisMPA that occurred during the synthesis. The thermal stability and glass transition temperatures of the hydroxyl-terminated hyperbranched polyesters were determined. Two hyperbranched urethane metbacrylates were synthesized by modifying 100 and 50% of the hydroxyl groups of G1 and G3, respectively. Their molecular structures were identified using IR and H-1 NMR spectroscopy, and their thermal properties were also investigated. (C) 2008 Wiley Periodicals, Inc.