Porous　carbon　materials　have　been　widely　used　as　electrode　materials　for　supercapacitors.　However,　low　specific　capacitance　severely　hinders　the　practical　application.　To　further　improve　the　capacitance,　this　work　reports　a　facile　approach　to　prepare　N,　S　co-doped　hierarchical　porous　carbon/MnO2　composites　(NSPC/MnO2).　Acidified　thiourea,　acting　as　N　and　S　source,　is　used　to　crosslink　sodium　alginate　(SA)　to　give　SA-based　composite　gels　which　are　pyrolyzed　to　produce　NSPC/MnO2.　X-ray　diffraction　and　X-ray　photoelectron　spectra　proved　that　manganese　exists　in　the　porous　carbon　in　the　form　of　MnO2.　The　obtained　NSPC/MnO2　exhibit　hierarchical　porous　structure,　remarkable　mesoporous　feature　(the　proportion　of　mesopores　and　macropores　reached　32.69%),　and　high　specific　surface　area　of　1701　m2　g−1.　Meanwhile,　NSPC/MnO2　show　abundant　heteroatom　doping,　i.e.　Mn　(2.05　at%),　N　(6.76　at%),　and　S　(2.16　at%),　which　provided　plenty　of　pseudocapacitance.　The　electrochemical　tests　show　that　NSPC/MnO2　as　electrode　material　can　reach　a　high　specific　capacity　of　281.1　F　g−1　at　1　A　g−1　(which　is　almost　1.85　times　higher　than　the　comparative　sample),　with　good　cycling　stability　(86.02%　after　5000　cycles　at　10　A　g−1).　©　2022　Elsevier　B.V.