The surface properties of Fe-based perovskite-type oxides with the formula La0.6Sr0.4CoyFe1-yO3-delta for y = 0. 1, 0.2, and 0.3 were investigated. Using methanol as a probe molecule, the amounts of basic and Lewis surface sites were determined. The types of sites were confirmed using DRIFTS. The surface basicity, as well as the reducibility, oxygen storage capacity, transition metal surface concentration, and methanol oxidation activity, were found to progress through an extrema for the intermediate Co level; that is, the behavior and performance of the samples are nonlinear with respect to increasing Co content. An electronic structural transition is proposed as the explanation for the observed trends. (C) 2007 Elsevier Inc. All rights reserved.