An AB(2) monomer containing one oxazoline and two phenolic units was synthesized. The polymerization of the monomer 2-(3,5-dihydroxyphenyl)-1,3-oxazoline in N-methylcaprolactam resulted in a well-defined and fully soluble, high molar mass, hyperbranched polymer with etheramide structure. The hydrolysis of some oxazoline groups as side reaction limits the achieved molar mass when the polymerization is carried out in tetramethylene sulfone or in bulk. The polymers were characterized by one (1D) and two (2D) dimensional H-1 and C-13 NMR spectroscopy which allowed to determine the degree of branching to be 50% as expected from statistics. DSC and TGA measurements revealed a glass transition temperature of 176 degrees C and a decomposition onset of 330 degrees C. The thermal ring-opening reaction was studied in situ by DSC measurements.