Microstructural properties such as relative density, triple phase boundary length, specific surface area, tortuosity factors are often calculated for microstructure-based analysis and modeling of solid oxide fuel cells (SOFCs). A realistic representation of the microstructure is a challenging and important issue for both experiments and modeling. In the present study, statistical correlation functions and a volume expansion method are used to determine the representative volume element size for the analyses of (La0.6Sr0.4CoFe0.8O3-delta)-Fe-0.2 cathode microstructures in SOFCs. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.