A systematic method to obtain the optimal operating conditions of a fuel cell system is presented. This method is based on the coupling of a semi-empirical fuel cell stack model and an associated balance of plant (BOP) model with an optimization algorithm in order to efficiently explore the range of possible operating conditions. The approach described in the paper to obtain optimal operating conditions is applied to a fuel cell system designed to operate in two different applications: automotive and stationary. In both cases, the application of this methodology results in a set of optimal operating conditions that yields large improvements in the system performance. The optimization problem is solved for two different performance objectives: maximization of net system power and maximization of system exergetic efficiency. (c) 2006 Elsevier B.V. All rights reserved.