A method to reduce the model of a nonlinear dynamic fuel cell stack, which is suitable for control and fault detection studies, is presented. In order to model the fuel cell stack, we have assumed that the fuel cells are arranged in a stack, electrically in series, with thermal and electrical contacts. Since in practical applications a stack may be composed of several (at least fifty) fuel cells, such model will be a large set of differential equations which may be difficult to simulate especially in control applications. In this paper, first, a model for an isolated fuel cell will be given. Then, a model for the temperature distribution in a fuel cell stack will be pursued. Finally, the use of an orthogonal collocation method to reduce the size of the model of the fuel cell stack without changing the model transient or steady state characteristics will be presented
