Covalent Organic Frameworks (COFs) based on polyimine with several metal ions (Fe^III, Co^II and Ni^II) adsorbed into their cavities have shown the ability to generate N-doped porous graphene from their pyrolysis under controlled conditions. These highly corrugated and porous graphene sheets exhibit high values of specific capacitance, which make them useful as electrode materials for supercapacitors.