Nanocrystalline, oxygen-deficient perovskite materials-Ce-doped Ba2In2O5-delta (BIC) and Zr-doped Ba2In2O5-delta (BIZ) powders have been successfully synthesized via reactive spray deposition technique processing. The mean particle size, surface areas, and phases of BIC and BIZ powders were analyzed. The transmission electron microscopy images showed a particle size of similar to 10 nm and the existence of nanopowder agglomeration. The sintering studies of the nanopowders of BIC and BIZ indicated that the grain size increases significantly with calcining temperatures beyond 1250 degrees C. The BIC sintered at 1250 degrees C showed much higher electrical conductivities than that sintered at 1500 degrees C. (c) 2006 The Electrochemical Society.