The bulk structure and surface properties of Fe-based perovskite-type oxides with the formula 12(0 6)Sr(0 4)Co(y)Fe(1-y)O(3-delta) for y=0 1 0 2 and 0 3 have been investigated The properties were found to strongly depend upon Co content temperature and environment The materials were selected due to their potential use as solid oxide fuel cell cathodes The intermediate Co loading formed oxygen vacancies most easily and several other properties including oxidation activity and surface sites showed a similar non-linear trend Trends are related to a possible transition in electronic structure Activity for oxidation of methane oxygen storage and chemical compatibility was shown to be superior to that of the La0 6Sr0 4MnO3 (C) 2010 Elsevier B V All rights reserved