Development of high-performance electrode materials is critical to the commercial realization of solid oxide fuel-cell (SOFC) technology. The material development process is, however, very complex and requires understanding of the fundamental issues of the materials and the electrochemistry that is involved. An interesting example is the (La,Sr)MnO3 (LSM) cathode material. This paper discusses some important issues in the development and optimization of LSM cathode materials for SOFCs. The relationship between the microstructure, interfacial properties and the electrochemical behaviour of the cathode material is not a static one. Rather, it changes and evolves constantly under fuel-cell operation conditions. Such dynamic relationship between the properties and the electrochemical behaviour is important for the fundamental understanding of the mechanism and kinetics of the oxygen reduction at LSM cathodes, and for the development of high-performance cathodes for SOFCs that operate at intermediate temperatures (600-800 degreesC). (C) 2003 Elsevier B.V. All rights reserved.