We herewith report the thermal, mechanical (modulus), and dielectric properties of polystyrene (PS)/expanded graphite (EG) nanocomposites fabricated by a simple technique of dispersing EG (Lip to 2.5 vol %) in PS matrix Via solution Method followed by hot pressing. The thermal stability and char yield of the nanocomposites are improved marginally. The modulus, electrical conductivity dielectric constant, and dielectric loss tangent of the nanocomposites are significantly increased with EG content. The modulus of the nanocomposites increases by about twofold at 30 degrees C compared with that of pure PS. The dielectric constant and the loss tangent of nanocomposites are increased Lip to 13-fold and 200-fold compared with that of pure PS, respectively, at 1 MHz and varied with frequency. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2071-2077, 2009