Hyperbranched polyesters containing labile triazene units in the main chain have been characterized according to their photochemically and thermally induced decomposition behavior. Irradiation with UV light results in a first order decomposition behavior with half-time of 6 to 48 min depending on the structure of the repeating unit. Thermal decomposition starts at about 160degreesC, and about 50% mass loss are achieved after 15 min at 250degreesC. Homogeneous incorporation of these globular, functional polymers in thermostable polymer matrices (polyimides and benzocyclobutane-based polymers) was possible. Smooth films from blends of thermostable matrix and up to 50% hyperbranched polymers could be prepared. The hyperbranched component could be destroyed selectively, and the resulting porous matrix has been studied as insulating material for microelectronic multilayer applications.