A dynamic simulator has been built for a 250 kW ER-molten carbonate Fuel cell (MCFC) system in order to study the controllability of this system. The tool has a modular set-up and will be used for designing the control system of more advanced MCFC systems, such as the SMARTER system, or can be adapted for systems based on other types of Fuel cell, such as phosphoric acid fuel fell (PAFC), solid polymer fuel cell (SPFC) or solid oxide fuel cell (SOFC).