The impedance of composite anodes for solid oxide fuel cells was modelled by three-dimensional impedance networks. These networks were generated by identifying neighbours in computer-generated random packings of electrode and electrolyte particles. The impedance of the networks was then calculated from Kirchhoff’s current law, assuming for the impedance of a single electrode-electrolyte interface the impedance of a generic three-step reaction pattern. The shape of the impedance-plane plot for the composite will, in general, differ significantly from that of the single electrode-electrolyte interface. These differences appear as a distortion of the spectrum at high frequencies, in some cases even as clearly distinguishable extra arcs. The nature and strength of the distortions will depend on the volume fraction of electrode particles, impedance parameters, conductivities and geometrical factors. The results are explained by the presence of electrode-particle clusters entirely confined within electrolyte clusters. Since the interfacial impedance of the former occurs partly in parallel with the ohmic resistance of the latter, additional time constants may appear in the impedance of the composite.