The oxygen exchange and transport properties of the perovskite-type oxides Ba0.5Sr0.5Co0.8Fe0.2O3-x (BSCF5582) and Ca0.5Sr0.5Mn0.8Fe0.2O3-x (CSMF5582) are investigated by oxygen permeation as well as electrical conductivity relaxation experiments. The temperature dependence of the oxygen permeation flux J(O2) of BSCF5582 in the range 600 <= T/degrees C <= 950 shows a transition from a low temperature region with higher activation energy to a high temperature region with lower activation energy. Complementary, the chemical surface exchange coefficient k(chem), the chemical diffusion coefficient D-chem and their activation energies are determined from conductivity relaxation experiments in the ranges 600 <= T/degrees C <= 750 and 70 < pO(2)/Pa < 3000. (c) 2008 Elsevier B.V. All rights reserved.