AbstractCeramic nanoparticles, that is, SiO2, TiO2, and Al2O3nanoparticles, with increasingly high thermal conductivity (λ), represent good candidates for improving the thermophysical properties of epoxy resins. In this study, the influence of filler addition on the thermal, mechanical, and dielectric properties were investigated by means of differential scanning calorimetry, dynamic mechanical analysis, and dielectric spectroscopy to measure λ, storage and loss moduli, dielectric permittivity, and volume resistivity. Moreover, morphological investigations by scanning electron microscopy were performed to confirm the particle dispersion into the epoxy matrix. The results show that both the elastic modulus and glass‐transition temperature increased with particle content. An enhancement of λ was also observed at high filler contents because of the formation of heat conductive pathways within the matrix. The nanocomposites' relative permittivity at 50 Hz was lower, whereas the dielectric loss was slightly higher compared with that of the neat epoxy matrix. A decrease in the relative permittivity with increasing frequency, both for the unfilled epoxy resin and epoxy–nanocomposites, was observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011