The main issue in preparing fuel cell systems for the future market is system reliability and efficiency. Apart from successful field test trials. any type of stationary, in general automotive or portable fuel cell systems are at the development stage. One task to deal with is to increase the component and system efficiencies by facilitating the system construction Or eliminating parasitic components. With newly established effective standardised system and component tests, linked with a flexible modelling and Simulation environment, the development process and the determination of the system efficiencies as well as the inaccessible system values can be accelerated. In this work a modular model-aided system analysis and development environment is presented which has been evaluated and validated at the IWE. The tool, a combination of standardised testing. modelling and simulation, has been applied to different types Of fuel cell systems showing the tool flexibility, modularity and accuracy. In the presented case the tool Was used for system analysis and studies on efficiency increase of a complex prototype stationary PEMFC system. (C) 2008 Elsevier B.V. All rights reserved.