A kW-class molten carbonate fuel cell with direct internal reforming is presented. Within an additional preheating framework, the estimation and control technique is implemented to this kind of nonlinear systems. By the proposed algorithm, the steady-state optimization algorithm subject to prescribed physical constraints is used to determine the desired operating condition, an open-loop observer design provides effective state estimation, and the nonlinear feedback control ensures the bounded stack temperature regulation in spite of unknown inlet perturbations. Finally, the proposed control methodology is successfully verified by numerical simulations. (C) 2010 Elsevier Ltd. All rights reserved.