The present study concerns the preparation of the nano-structured LSM/ScSZ composite powder material by spray pyrolysis which was previously proved to be effective in realizing extremely fine cathode microstructures. Based on an investigation into the detailed processes of evaporation, dehydration, decomposition and crystallization during the course of the powder preparation, a comprehensive model explaining the entire process from powder preparation to cathode fabrication is proposed. It is also clearly demonstrated that the complete elimination of nitrate compounds from the as-prepared powder material is essential for successful cathode fabrication and that the maximum process temperature during the spray pyrolysis is thus a key controlling parameter in the powder preparation. The present result can provide a valuable insight into controlling extremely fine cathode microstructures with the proposed pre-fabricated composite powder material. (C) 2007 Elsevier B.V. All fights reserved.