Performance and availability of molten carbonate fuel cells (MCFC) stack are greatly dependent on its operating temperature. Control of the operating temperature within a specified range and reduction of its temperature fluctuation are highly desirable. The models of MCFC stack existing are too complicated to be suitable for design of a controller because of its lack of clear input-output relations. In this paper, according to the demands of control design, a quantitative relations model of control-oriented MCFC between the temperatures of the stack and flowrates of the input gases is developed, based on conservation laws. It is an affine nonlinear model with multi-input and multi-output, the flowrates of fuel and oxidant gases as the manipulated vector and the temperatures of MCFC electrode-electrolyte plates, separator plates as the controlled vector. The modelling and simulation procedures are given in detail. The simulation tests reveal that the model developed is accurate and it is suitable to be used as a model in designing a controller of MCFC stack. Copyright (C) 2004 John Wiley Sons, Ltd.