Polymeric nanocomposites of high thermal conductivities are developed for their significant potential applications in modern electronics, transportation, and space technologies. Among widely studied nanoscale fillers are carbon nanomaterials of superior thermal transport characteristics, whose incorporation into polymeric matrices may result in nanocomposites that exhibit a good combination of processability and thermal conductivity. In this work we prepared specifically exfoliated few-layer graphene nanosheets (GNs), and dispersed them into two different polymeric matrices, the poly(ethylene-vinyl acetate) copolymer (PEVA) and polyimide (PI). The GNs, generally less than 10 nm in thickness according to X-ray and microscopy characterization results, were found to substantially enhance the thermal transport properties in the resulting polymeric nanocomposite films. The same enhancement was also found in the devices fabricated from the nanocomposites, specifically tubes from melt-extrusion, suggesting significant application potentials of the polymeric/GN nanocomposite materials. The ability for the GNs to impart electrical conductivity into the nanocomposite films was also determined, with the results correlated in terms of the percolation theory. The relative enhancement effects of the GNs at different loadings in the nanocomposite films on thermal and electrical transports are highlighted and discussed. (C) 2012 Elsevier Ltd. All rights reserved.