Oxygen tracer diffusion (D*) and chemical diffusion ((D) over tilde) were measured in dense Sr0.5Sm0.5CoO3-delta (SSC) ceramics by Isotope Exchange Depth Profiling/Secondary Ion Mass Spectrometry (IEDP/SIMS) and electrical conductivity relaxation (ECR) over the temperature ranges of similar to 100-200 degrees C and 400-600 degrees C, respectively. In addition, the surface exchange coefficients were determined over the same temperature ranges. The transport properties and exchange kinetics of SSC are comparable to or better than those of other solid oxide fuel cell cathode candidates in the literature. The ionic conductivity of SSC was calculated using the Nernst-Einstein equation, and is comparable to that of leading solid oxide electrolytes at intermediate temperatures. (C) 2012 Elsevier B.V. All rights reserved.