Disclosed are processes for producing monolithic and metal doped monolithic porous carbon disks from prepolymer organic precursors in the powder form composed of either or both polyimide and polybenzimidazole. The powders are consolidated (compressed) into disks and then pyrolyzed to form the desired porous carbon disk. Porous carbon-carbon composite disks are also prepared by adding carbon to the prepolymer organic precursors.