The numerical model of a solid oxide fuel cell fuelled with methane via an internal reforming is presented in the paper. The model has been implemented into the commercial CFD code. The basic model for fuel cell fed with humidified hydrogen has been extended to cope with mixture of hydrogen, carbon monoxide and methane as a fuel. Numerical calculations have been performed to predict the tubular fuel cell performance for various current densities, electrochemical reaction rate ratio and steam-to-carbon ratio.