A polymeric nanocomposite system (nanodielectric) was fabricated, and its mechanical properties were determined. The fabricated nanocomposite was composed of low concentrations of monodispersed titanium dioxide (TiO2) nanoparticles and an epoxy resin specially designed for cryogenic applications. The monodispersed TiO2 nanoparticles were synthesized in an aqueous solution of titanium chloride and polyethylene glycol and subsequently dispersed in a commercial-grade epoxy resin (Araldite® 5808). Nanocomposite thin sheets were prepared at several weight fractions of TiO2. The morphology of the composites, determined by transmission electron microscopy, showed that the nanoparticles aggregated to form particle clusters. The influence of thermal processing and the effect of filler dispersion on the structure–property relationships were identified by differential scanning calorimetry and dynamic mechanical analysis at a broad range of temperatures. The effect of the aggregates on the electrical insulation properties was determined by dielectric breakdown measurements. The optical properties of the nanocomposites and their potential use as filters in the ultraviolet–visible (UV–vis) range were determined by UV–vis spectroscopy. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers