In this report, a solid oxide fuel cell (SOFC) system with fuel recycling was proposed, and its generation efficiency was evaluated. In the system, ail of the fuel supplied is utilized for generation, and the open-circuit voltage is enhanced by the removal of CO2 and H2O from recycled fuel. Fuel recycling improves the generation efficiency of the SOFC system if the energy required for the separation of CO2 and H2O could be reduced to close to the separation free-energy.