Internal steam reforming in SOFC cells leads to inhomogeneous temperature distributions according to the fast reforming reaction kinetics. This results in thermal induced stresses and may lead therefor to mechanical failure of the material. A one-dimensional numerical simulation program has been developed to describe the transport of gases inside the SOFC anode due to diffusion and permeation as well as the kinetic of the reforming reaction and the electrochemistry. Simulations with experimentally determined reaction rates and structural properties of the anode materials have been performed. In order to reduce the methane conversion rate, a sensitivity analysis has been performed. It can be shown, e.g., that a reduction of the structural parameter psi which is the ratio of porosity epsilon to tortuosity delta of 26.28% compared to standard material leads to a lowering of the methane conversion rate of 12.24%. Finally, produced cermets are screened in view of a conversion lowering effect. (C) 2000 Elsevier Science S.A. All rights reserved.