A series of hyperbranched aliphatic-aromatic polyesters has been synthesized which contain vinyl ether or oxetane functionalities as curable groups. We investigated the curing behavior of these multifunctional polymers in the presence of reactive diluents in order to analyze the possibility of their application in high solids coatings. The vinyl ether-modified hyperbranched polyesters with a high degree of modification yield the best coatings. Furthermore, coating systems containing vinyl ether-modified hyperbranched polyesters and triethyleneglycol divinyl ether (DVE-3) as reactive diluent showed a better performance compared to those containing 4-hydroxybutyl vinyl ether (HBVE). Real time FT-IR studies revealed a high conversion of functional groups (76%) for the cationic curing with DVE-3. On the other hand, the curing reaction of the functional hyperbranched polymers without the presence of any reactive diluent stopped at 32% conversion of functional groups due to the reduced mobility of the polymer. The vinyl ether-modified hyperbranched polyester could be cured also radically in the presence of diethyl maleate (DEM) as reactive diluent, whereas the curing of the oxetane-modified polyesters was very slow and incomplete in all attempts.