In this paper, we present a simple solid oxide fuel cell (SOFC) power system fed by methane gas. Comprehensive thermodynamic modelling was conducted on this simple SOFC power system supplement with some details of gas dynamics in the piping linking the system components. The system consists of a fuel cell stack, two heat exchangers for preheating fuel and air streams, an afterburner to burn off the residual fuel, a vaporiser for vaporising water, a mixer for mixing fuel and steam, a reformer to produce hydrogen-rich reformate and a steam boiler serves to balance the heat of the power system. Results showed that at 70% of fuel utilisation rate, 1 atm of fuel and air flow pressure, 1173 K of fuel inlet temperature and 973 K of air inlet temperature, the SOFC plant can achieve first and second law efficiency of 47.0% LHV, and 48.9%, respectively. (C) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.