The self-diffusion coefficient (D*) and oxygen surface exchange coefficient (k) for La 0 . 6 Sr 0 . 4 Co 1 - x Ni x O 3 - δ (LSCN, where x=0.02) were measured over the temperature range 400-700 o C using Isotopic Exchange Depth Profile and Secondary Ion Mass Spectroscopy techniques (IEDP/SIMS). From this, the activation energy for oxygen diffusion was calculated to be 134 kJ/mol. In addition, the electrochemical impedances of porous LSCN and composite LSCN/Ce 0 . 9 Gd 0 . 1 O 1 . 9 5 (CGO) cathodes were measured by AC impedance spectroscopy. Adding ionic conducting CGO to the mixed conducting LSCN was found, to a certain extent, not to have an adverse effect on electrode properties.