The synthesis and properties of novel hybrid silsesquioxane-containing urethane polymers using octakis(hydroxypropyldimethylsiloxy)octasilsesquioxane (OHPOSS) as a crosslinker and a hydroxyl-terminated polybutadiene were studied. Mixing of the OHPOSS with polyurethane prepolymer and chain extenders in solution was found to be successful when tetrahydrofuran was used as the solvent. Thin films of hybrid polyurethanes were obtained. The hybrid materials were elastomers with improved water and solvent resistivity and good thermal stability. The studied OHPOSS appeared to be an effective crosslinker of polyurethanes suitable for, for example, surface coatings applications. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2023-2030, 2013