A novel, photodefinable, high dielectric constant (high-k) nanocomposite material was developed for embedded capacitor applications. It consists of SUS as the polymer matrix and barium titanate (BT) nanoparticles as the filler. The UV absorption characteristics of BT nanoparticles were studied with a UV-Vis spectrophotometer. The effects of BT nanoparticle size, filler loading, and UV irradiation dose on SUS photopolymerization were systematically investigated. The dielectric properties of the photodefined SU8 nanocomposites were characterized. Embedded capacitors using the novel high dielectric constant SU8 composite photoresist were demonstrated on a flexible polyimide substrate by the UV lithography method. (c) 2006 Wiley Periodicals, Inc.