Mixed oxide-ion and electronic conductive thin films with the composition of (Ce0.85Sm0.15)O2-delta-15 vol%MnFe2O4 (CSO-MFO) were prepared on porous yttria stabrized zirconia substrates by a spin coating process, and their oxygen permeation flux densities were measured. The porous substrates were prepared from ZrO2-3 mol%Y2O3 (3YSZ)-33 vol%carbon and NiFe2O4. 3YSZ porous substrates were obtained from 3YSZ-33 vol%carbon by sintering at 1350 degrees C under At for 5 h and following oxidation at 800 degrees C under air for 2 h. For 3YSZ-33 vol%NiFe2O4, the optimum condition was sintering at 1400 degrees C under air for 5 h and following reduction at 800 degrees C under H-2 for 2 h. A CSO-MFO film was prepared by a spin coating process on the substrate. The thickness of the CSO-MFO was approximately 150 nm. Oxygen flux density of the CSO-MFO sample was found to be 8.9 x 10(-8) mol.cm(-2).s(-1).