Integration of biomass gasification with solid oxide fuel cell (SOFC) offers an emerging alternative for future sustainable power generation. In the present paper a comparative exergoeconomic analysis of using steam and air as two different gasification agents is performed on an integrated biomass gasification-SOFC system. The system performance is optimized based on the net output power, exergy efficiency and the unit product cost of the system. A detailed thermodynamic equilibrium model for gasification process is developed and verified by reliable available data. A parametric study is conducted to examine the effects of key operating parameters on the net output power, exergy efficiency and unit product cost of the integrated system. The results indicate that, at the optimal operating conditions when steam is used instead of air as the agent, the net output power is increased by 14.8%, the exergy efficiency is increased by 24.9% and the unit product cost of the system is decreased by 8.9%. (C) 2019 Elsevier Ltd. All rights reserved.