X-ray diffraction, at high Ts and switching between N-2/air atmospheres, was used to compare the chemical expansion due oxygen non-stoichiometry variations between epitaxial films of different mixed ionic-electronic conductors: La0.6Sr0.4CoO3-delta(LSC), Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF), LaNiO3-delta(LNO), La2NiO4+delta(L2NO) and GaBaCo2O5.5+delta(GBCO) and La0.7Sr0.3MnO3-delta(LSM). LSC and BSCF show the largest relative change in the cell parameter Delta c/c = +0.5%, while L2NO and GBCO show negative Delta c/c = -0.2% and -0.1%, respectively. LNO and LSM show either reduced or negligible chemical expansions. In all cases the values correspond to their particular defect equilibrium and degree of charge localization. The oxygen surface exchange kinetics was also evaluated from in-situ time-resolved analyses of the cell parameter variations. LSC, LNO and GBCO films show fast oxygen reduction kinetics, k(chem) = 5 . 10(-6), 3.10(-6), and 2.10(-7) cm/s at 700 degrees C, respectively, in relative agreement with reported values, while BSCF films show much slower kinetics than expected, below k(chem) = 10(-7) cm/s at 650 degrees C, related to the degradation process observed in the films. (C) The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: [email protected]. All rights reserved.