Although the cermet consisting of nickel and zirconia is useful as the solid oxide fuel cell anode, the conventional cermet consisting of nickel and yttria-stabilized zirconia (Ni/YSZ) is prone to be deactivated for a direct supply of hydrocarbon fuels. This paper describes a method to retard the deactivation of the Ni/YSZ-based cermet anode by being modified with appropriate incorporation of Co as the alloying element into Ni. The single-type anode-supported solid oxide fuel cell (SOFC) consisting of the Ni_0.75Co_0.25/YSZ cermet anode, YSZ film electrolyte, and La_0.8Sr_0.2MnO₃ cathode exhibited a prolonged stable SOFC performance at 750°C for dry methane (CH₄) feeding compared to the one using the Ni/YSZ anode. The microstructural modification of the cermet anode caused a carbon tolerance effect against CH₄ accompanied by a low anodic polarization resistance.