The anodic performance enhancement of solid oxide fuel cells (SOFCs) by introducing penetrating electrolyte structures was investigated using a random resistor network model considering the transport of electrons and ions, and the electrochemical reaction in composite anodes. The composite anode was modeled as a mixture of ionic and electronic particles, randomly distributed at simple cubic lattice points. The dependence of the anodic polarization resistances on the volume fraction of the electronic phase, the thickness of the anode, and the insertion of various penetrating electrolyte structures were explored to obtain design criteria for best performing composite anodes. The network simulation showed that the penetrating electrolyte structures are advantageous over flat electrolytes by enabling more efficient use of electrochemical reaction sites, and thereby reducing the polarization resistances. (C) 2004 Elsevier B.V. All rights reserved.