For the seven technically feasible Biomass-Integrated Gasification Fuel Cell (B-IGFC) systems investigated in this two-part system analysis, the interactions between the used biomass gasification processes, gas processing technologies and SOFC concepts are investigated primarily employing ASPEN PLUS (TM) flowsheeting models. Based on the results of the system simulations, the power production costs are estimated for the various B-IGFC systems. The impact of the most important assumptions made for the presented thermo-economic system analysis is assessed through a sensitivity analysis. It is found that the efficiency losses of the gasification process can hardly be compensated in the latter parts of the investigated B-IGFC systems. Thus, updraft gasification based systems yield the highest system efficiencies. The air-to-fuel ratio is highly cost effective as it determines the size of the heat exchangers and the power requirement of the cooling air blower, which both are the major cost drivers in the investigated B-IGFC systems. It was found that 55 to 70% of the power production costs are directly related to the specific plant costs while the remainder is determined by the system efficiency. The analysis revealed that it does not pay out to increase the system efficiency by increasing the operational voltage. This is beacuse the resulting decreased mean current density yields strongly increased specific plant costs and thus power production costs. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.