Microstructures ofNiO and samaria-doped ceria (SDC) composite particles synthesized by spray pyrolysis method and porous cermets sintered at various temperatures were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the particles had hollow structures, and the element mapping analysis showed that cerium was concentrated in the vicinity of the particle surface and nickel was distributed uniformly inside the particles. SEM images of the sintered centre showed that the composite powder started connecting at around 1100°C. TEM measurement of the sintered cermet at 1150°C indicated that SDC on the surface of each particle was connected at the early stage of sintering. Aggregation of nickel can be prevented by the presence of SDC between particles at the early stage of sintering, and Ni-SDC anode gives very low polarization of less than 40 mV with a high current density of 0.9 A/cm 2 at 800°C.