To study the effect of nonequal reactivity of B units in AB(x) monomers, two novel monomers for synthesis of hyperbranched polymers of the polyaddition type, namely 2-(2,5-dihydroxyphenyl)-2-oxazoline (2a) and 2-(2,4-dihydroxyphenyl)-2-oxazoline (2b) were prepared and characterized. Both monomers have one free phenolic group and one hydrogen-bonded phenolic group with the difference in chemical shift more than 2 ppm. Both monomers undergo thermally initiated polymerization in bulk and in solution at the temperature 220 degrees C during 1 h in bulk and 24 h in solution of 1-chloronaphthalene. Products are white powders with degree of polymerization 17 and 13 for the respective polymer 3a and 3b. The degree of branching is 0.37 and 0.3 for the respective polymer. The structure of polymers is in agreement with the structure, which was expected from the structure of monomers and consists of linear, dendritic, and terminal units.