Epitaxial La0 6Sr0 Co-4(0) Fe-2(0) O-8(3-delta) (LSCF) thin films have been grown successfully on single crystal LaAlO3 substrate by pulsed laser deposition (PLD) AFM micrographs have shown a rms roughness of 5A for the 550 degrees C deposited films The films further exhibited electrical conductivities of as high as 2 3 x 10(3) S cm(-1) at 600 degrees C with an activation energy of 0 09 eV The surface exchange coefficient (k(chem)) of the epitaxial LSCF thin film determined by electrical conductivity relaxation (ECR) technique increased with the increasing temperature and reached a value of similar to 5 1 x 10(-6) S cm(-1) at temperatures above 620 C (C) 2010 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved