In　this　paper,　we　introduced　light　and　abundant　metal　magnesium　into　a　cobalt-based　metal　organic　framework　(Co-MOF,　[(CH3)2NH2]2[Co3(bpdc)4]·5DMF·4CH3OH)　(1,　H2bpdc　=　4,4′-biphenyldicarboxylic　acid,　DMF　=　N,N-dimethylformamide)　as　a　heteroatom　to　synthesize　Mg-Co　bimetallic　MOFs,　namely　[(CH3)2NH2]2[MgCo2(bpdc)4]·4DMF·5CH3OH　(2)　and　[(CH3)2NH2]2[Mg1.2Co1.8(bpdc)4]　4DMF·4CH3OH·6H2O　(3).　Based　on　the　formation　of　a　rather　low　density　framework　after　the　introduction　of　the　light　Mg2+,　such　bimetallic　MOFs　exhibited　higher　gas　adsorption　abilities　than　the　isostructural　Co-based　MOF　1.　N2　adsorption　measurements　demonstrate　that　the　BET　surface　area　of　3　is　305.4　m2　g-1,　exhibiting　three　times　that　of　1　(104.4　m2　g-1).　Significantly,　due　to　the　introduction　of　the　low-melting　Mg2+,　the　Mg-Co　MOFs　could　be　further　utilized　as　precursors　for　porous　carbons　only　by　calcination　at　a　mild　temperature　of　600　°C　which　could　exhibit　a　BET　surface　as　high　as　712.78　m2　g-1.　Furthermore,　after　post-synthetic　modification　with　a　N/S　heteroatom　at　900　°C,　the　obtained　hierarchical　carbons　exhibit　superior　activity　in　the　oxygen　reduction　reaction　(ORR)　that　is　comparative　to　the　commercial　Pt/C　catalyst.　TEM　results　indicate　that　Co-embedded　carbon　nanotube　(CNT)-containing　hierarchically　nanoporous　carbons　have　been　obtained.　This　study　may　offer　a　new　avenue　to　prepare　porous　carbons　utilizing　Mg-containing　bimetallic　MOFs　as　sacrificial　templates.　©　2018　The　Royal　Society　of　Chemistry.