The thermal and electrical conductivity of monolithic carbon aerogels was investigated at room temperature. Results showed both the solid thermal conductivity and the electrical conductivity scale with the density in the range between 60 and 650 kg m−3. The scaling exponents for the two conductivities have identical values of 1.5. For a density of 82 kg m−3a thermal conductivity of 0.029 W m−1 K−1in air and 0.018 W m−1 K−1after evacuation was found.