Direct　internal　reforming　is　one　of　the　promising　methods　of　utilizing　hydrocarbon　fuels　in　solid　oxide　fuel　cells　(SOFCs).　Among　direct　internal　reforming　technologies,　dry　reforming　of　methane　(DRM)　is　attracting　attention　as　an　alternative　to　steam　reforming　of　methane.　In　this　study,　a　cermet　material　composed　of　nickel　and　samarium-doped　ceria　(Ni-SDC)　was　investigated　as　an　SOFC　anode　for　the　direct　internal　DRM　operation.　Compared　to　a　conventional　nickel-yttria-stabilized　zirconia　(Ni-YSZ)　anode,　the　Ni-SDC　anode　showed　superior　current-voltage　characteristics.　However,　poor　carbon　balances　were　recorded　in　anode　outlet　gas　analysis,　indicating　coke　formation　on　the　Ni-SDC　anode.　The　addition　of　calcium　to　the　Ni-SDC　anode　was　also　tested.　Measured　anode　outlet　gas　compositions　suggested　that　the　calcium　addition　suppressed　coke　formation,　while　the　power　generation　performance　of　the　pristine　Ni-SDC　anode　was　maintained.　Microscopic　observations　showed　that　a　certain　part　of　the　calcium　additive　existed　as　CaO　particles　on　the　anode　surface,　which　could　be　responsible　for　the　improved　coking　resistance.　©　2020　The　Electrochemical　Society　(“ECS”).　Published　on　behalf　of　ECS　by　IOP　Publishing　Limited