This research emphasizes on the development of highly filled graphene-polybenzoxazine composites and investigates thermal, electrical, and mechanical properties of the obtained composites for bipolar plate applications. The composition of graphene loading was achieved to be in the range of 10-60 wt%. The experimental results revealed that at the maximum graphene content of 60 wt% (44.8 vol%) in the polybenzoxazine, storage moduli at room temperature of the composites were considerably enhanced with the amount of the graphene, that is, from 5.9 GPa of the neat polybenzoxazine to about 25