Abstract <p>In the present study, highly filled composites based on the natural graphite-phenolic resin system with a filler content of 75–95 wt % were assessed. The influence of the type of filler particle size distribution on the functional characteristics of the composites was studied. It was shown that the thermal conductivity and electrical conductivity of the composites decreases exponentially with increasing filler grinding time. It was found that the selected manufacturing technology leads to the production of highly oriented materials with predominant orientation of the basal planes of filler particles perpendicular to the pressing axis, which leads to pronounced anisotropy of thermal and electrical conductivity (about 10). It was found that the best properties are achieved at filler content of 90 wt %: the average electrical conductivity was 401.4 S/cm; the thermal conductivity was 142.3 W/(m K); the heat capacity was 0.83 J/(g K); the flexural strength and modulus were 41.9 MPa and 24.4 GPa, respectively. The resulting compositions with high values of thermal and electrical conductivity showed promise for their use as materials for the manufacturing of heat-exchange electrically conductive surfaces, including bipolar plates of fuel cells.</p>