We have successfully fabricated (PrBa)Co<
sub>
2<
/sub>
O<
sub>
5+?<
/sub>
and (LaBa)Co<
sub>
2<
/sub>
O<
sub>
5+?<
/sub>
epitaxial thin film on various single crystal substrates. Physical and electrochemical properties characterizations were carried out. Highly conductive oxygen-deficient double perovskite LnBaCo<
sub>
2<
/sub>
O<
sup>
5+<
/sup>
thin films were grown on single crystal (001) SrTiO<
sub>
3<
/sub>
(STO), (001) MgO, (001) LaAlO<
sub>
3<
/sub>
and (110) NdGaO<
sub>
3<
/sub>
} substrate by pulsed laser deposition. Microstructure studies from synchrotron X-ray diffraction and Transmission electron microscopy. High temperature transport properties was carried in different atmosphere (O<
sub>
2<
/sub>
,Air, N<
sub>
2<
/sub>
) up to ~900K. Resistance response of (LaBa)Co<
sub>
2<
/sub>
O<
sub>
5+?<
/sub>
epitaxial thin film was characterized in oxygen, nitrogen and 4% hydrogen over a wide range of temperature from 400 C up to 800 C. To determine the electrode performance and oxygen exchange kinetics of PrBaCo<
sub>
2<
/sub>
O<
sub>
5+?<
/sub>
, multi-layered thin film based half cell was deposited on LaAlO<
sub>
3<
/sub>
(001) substrate. The temperature dependence of the resistance of this half cell structure was characterized by electrochemical impedance spectroscopy (EIS) within different temperature and gas environments. Anode supported fuel cells, with GCO:YSZ multilayer thin film as electrolyte and PBCO thin film as electrode, are fabricated on tape casted NiO/YSZ substrate. Full cell performance is characterized up to 800 C.