Abstract: This invention relates to use of a specific class of carbon structures in non-conductive materials in order to enhance the electrical- and/or the thermal conductivity of the materials. This invention is based on the discovery that a class of micro-domain carbon particles known as carbon cones and disks are excellent conductive filler in plastics with a critical loading level of approximately 1 weight %, which is comparable with the performance of carbon nanotubes. But, these carbon structures may be produced in industrial scale at the same cost as carbon black. Thus it is possible to provide thermal- and electric conducting composite materials with almost the same density and mechanical properties as the pure matrix material at the favourable cost of carbon black as filler.