In the present work, the methods, techniques and results obtained during the studies of biomass fuelled molten carbonate fuel cell (MCFC) systems within the Swedish national fuel cell program are presented. The power plants are 60 MW class, utilising biomass (i.e. wood chips) as the primary fuel. The biomass is converted via pressurised gasification into a gaseous form that, after subsequent cleaning, can be used in the fuel cells. An investigation of the effects of gasification pressure, temperature and the influence of internal reforming on the overall system performance is presented. All studies were carried out using the Aspen Plus(TM) with Model Manager(TM) simulation package.