The incorporation of electrical and thermal conductive fillers in polymers is of great interest for electrochemical applications such as bipolar plates to replace metals in the fuel cell technology. The durability of bipolar plates based on thermoplastic composites and their production are not yet satisfactory due to the high proportion of the conductive filler and the resulting embrittlement. Therefore there is a need to reduce the proportion of the conductive filler on a high level (e.g. single or hybrid filler systems of carbon based fillers) and to improve the mechanical properties by blending with a suitable impact modifier. In this study, composites based on polypropylene (PP) and different filler systems were melt mixed using small scale microcompounder Xplore DSM15 as well as lab scale co-rotating twin-screw extruder Coperion ZSK26Mc. The measurements of the electrical and thermal conductivity as well as mechanical properties of the composites were performed on pressed plates. It was found that the addition of synthetic graphite powders having different particle size distributions leads to different increases of the thermal conductivity. The highest value was measured for composites containing TIMCAL Timrex® KS500. The electrical volume conductivity was detected around 5 S/cm at 80 wt.-% graphite. Furthermore, the influence of styrene-ethylene-butylene-styrene block copolymer (SEBS) based impact modifier on the mechanical properties of PP filled with 80 wt.-% of different synthetic graphite was investigated. For that the proportion of SEBS in the PP component was varied systematically. The conductivities were influenced by the kind of graphite and the content of impact modifier. The results indicate that the impact strength of the composite containing TIMCAL Timrex® KS500 can be increased by approx. 100% when replacing 50 wt.-% of the PP component by SEBS.