The electrochemical properties of La0.5Sr0.5Co0.8M0.2O3- (M=Mn, Fe, Ni, Cu) cathodes are investigated with chemical bulk diffusion coefficients (D-chem) and polarization resistances. The electrochemical performance of long-term testing for La0.5Sr0.5Co0.8Cu0.2O3- cathode was carried out to investigate its electrochemical stability. In this work, an anode-supported single cell with a thick-film SDC electrolyte (30 m), a Ni-SDC cermet anode (1 mm), and a La0.5Sr0.5Co0.8Cu0.2O3- cathode (10 m) reaches a maximum peak power density of 983 mW/cm(2) at 700 degrees C. Obviously, Cu substitution for B-site of La0.5Sr0.5CoO3- cathode reduced thermal expansion coefficient (TEC) value and enhanced oxygen bulk diffusion and electrochemical properties. La0.5Sr0.5Co0.8Cu0.2O3- is a promising cathode material for intermediate temperature solid oxide fuel cells (IT-SOFC).