The effect of parameters for composite powder preparation on the electrochemical performance of cathodes using mechanically prepared LSM/ScSZ cathode material for solid oxide fuel cells was evaluated. It revealed that the input process energy, which is defined as a time integration of required power for rotor blade driving, consistently described changes in the BET surface area and particle size distribution for composite powder material. Depending on the composite powder samples, however, bulk and interfacial resistances for a half-cell test sample varied in a more complex manner when the input process energy was changed. The present results indicated the importance of process parameters such as the input energy besides the absolute values and ratio of particle size for starting powders and the LSM/ScSZ composition ratio. It can be expected that the electrochemical performance may be further improved with precise matching and controlling of these parameters. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.