Electrostatic spray deposition (ESD) technique was used to fabricate dense Y2O3-doped BaZrO3 (BYZ) thin films, which have been extensively studied for the protonic ceramic fuel cell electrolyte. Effects of the ESD process parameters (i.e. substrate temperature, type of precursor, flow rate and applied voltage) on the microstructure of as-deposited films were studied. The uniform as-deposited films were obtained using a mixture of zirconium acetylacetonate, barium chloride dihydrate and yttrium chloride hexahydrate precursors in a solvent mixture of butyl carbitol and deionized water at a volume ratio of 50:50. The optimum deposition parameters were obtained at the substrate temperature of 250 degrees C with the applied voltage and now rate in a range of 10-12 kV and 1.4-2.8 ml/h, respectively. The as-deposited films were subsequently annealed at 1350 degrees C for 10 h to ensure the complete chemical reactions of the precursors. X-ray diffraction patterns reveal the perovskite structures of the annealed BYZ films (deposited on yttria stabilized zirconia substrates) with only traces of Y2O3 phase, which could arise from the loss of BaO at high annealing temperatures. (C) 2011 Elsevier B.V. All rights reserved.