Comparing with conventional solid oxide fuel cells (SOFCs) that typically operate at ~750 ^oC and above, intermediate temperature SOFCs (IT-SOFCs) that operate at temperature of ~400-700 ^oC offer advantages such as the possibility for the use of lower cost sealing and interconnect materials and the potential for improved reliability and robustness due to the expected slower degradation at reduced temperature.  For IT-SOFCs, proton-conducting oxides such as acceptor-doped Ba(Ce, Zr)O₃ are often preferred as the electrolyte materials for their high ionic conductivity and low electronic transport number while Ni is almost always used for the anode.  In comparison, researchers have not settled on a proper cathode or oxygen electrode, and various materials such as LSCF and SSC have been explored and show different degree of success.  Here, we report the use of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) as cathode material for proton conducting IT-SOFC with BaZr_0.1Ce_0.7Y_0.1Yb_0.1O₃ (BZCYYb) electrolyte.  In particular, the chemical stability of BSCF cathode subjecting to different atmospheres containing water (H₂O) vapor and CO₂ and the compatibility of BSCF with BZCYYb electrolyte will be examined.  In addition, the impacts of cell operating conditions including cathodic bias voltage, moisture and CO₂ on the electrochemical performance of cathode including bulk and interfacial resistance will be reported using cathode symmetrical cells and/or anode-supported button cells.  Preliminary results seem to suggest that BSCF cathode displays reasonable stability and compatibility under typical proton conducting IT-SOFC operating conditions, and cathode performance increases in humidified air compared with dry air.  Finally, the directions for future design of cathode for proton conducting IT-SOFC will be discussed.