The hydroxy end groups of aromatic and aliphatic hyperbranched poly-(urea urethane)s prepared with an AA* + B*B-2 one-pot method were modified with phenylisocyanate, butylisocyanate, and stearylisocyanate. The success of the modification reaction was verified with H-1 NMR and IR spectroscopy. Linear model poly(urea urethane)s were prepared, too, for comparison. The bulk properties of OH functionalized hyperbranched poly(urea urethane)s, compared with those of linear analogues and modified hyperbranched poly(urea urethane)s, were studied with differential scanning calorimetry, thermogravimetric analysis, and temperature-dependent Fourier transform infrared measurements. Transparent and smooth thin films could be prepared from all polymer samples and were examined with a light microscope, a microglider, and an atomic force microscope. The properties of the polymer surface were examined by measurements of the contact angle and zeta potential. For all samples, the properties were mainly governed by the strong interactions of the urea and urethane units within the backbone, whereas the influence of the nature of the end groups and of the branched structure was reduced in comparison with other hyperbranched polymer systems. (c) 2005 Wiley Periodicals, Inc.