This paper presents the work on a natural gas-fed integrated internal-reforming solid oxide fuel cell-gas turbine (IRSOFC-GT) power generation system. It was assumed that only hydrogen participated in the electrochemical reaction, while the non-reacted raw gases and reformed gases are fully oxidized in the combustor downstream of the fuel cell stack. The system consists of an integrated reformer, a SOFC stack, a combustor, a gas turbine and a power turbine, a fuel compressor and an air compressor, two recuperates and a heat recovery steam generator (HRSG). Different levels of modeling work for the fuel cell, fuel cell stack, and integrated system were conducted, which provide a means for sizing up the power system in the developmental stage. Simulation results show that the IRSOFC-GT power system could achieve a net electrical efficiency of better than 60% and a system efficiency (including waste heat recovery for steam generation) of better than 80%. (C) 2002 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.