NiO-Sm0.2Ce0.8O1.9 (NiO-SDC) composite particles were synthesized by spray pyrolysis (SP). SP resulted in composite particles of NiO enveloped with SDC and these capsule-type composite particles would reduce aggregation of Ni during the reduction from NiO to Ni metals. SOFC anode microstructures and morphologies of NiO-SDC composite precursor particles much affects on SOFC power densities or anode polarization. Therefore, we focused on atomizing conditions of SP process. Relationship between ultrasonic atomization conditions and morphologies of NiO-SDC composites were investigated by controlling temperatures of atomization vessels. The atomizing temperature changed concentration of mists in the vessel, and mean particle size and particle size distribution were increased with an increase in temperature of the atornization vessels. Some extremely large particles were observed by synthesizing at higher atornization temperatures. Large particles contained voids in the particles. The voids in the composite particles would play a role of pore-formers. SOFC measurement showed the synthesis at the atomizing temperature of 30 degrees C resulted in the high-performance anode. The atomizing process of SP much affected morphology of anode precursor particles, and the atomizing conditions were important to improve anode performance. (c) 2006 Elsevier B.V. All rights reserved.