In this initial study the electrochemically active region of a La0.8Sr0.2Co0.2Fe0.8O3-delta (LSCF) cathode was reconstructed in three dimensions using a focused ion beam/scanning electron microscope. The reconstructed volume totaled 1065 mu m(3) from the free air surface to the dense yttria-stabilized zirconia electrolyte interface. Various microstructural properties were measured, including overall porosity, closed porosity, graded porosity, surface area, tortuosity, triple-phase boundary length, and pore size. Electrochemical impedance spectroscopy data was correlated to microstructure. (c) 2007 The Electrochemical Society.