Pressurised black liquor gasification combined either with a gas turbine or a catalytic fuel synthesis process is a novel technique for production of green electricity or second generation motor fuels. The composition of the gas produced in the gasifier may be important for the performance of either the gas turbine or the catalytic fuel synthesis process and different operating parameters of the gasifier may affect the composition of the produced gas. The aim of this study was to investigate the influence of some operating parameters on the final gas composition with special attention on the performance of the quench in the gasifier. The results show that system pressure, oxygen/black liquor flow rate ratio and the primary spray flow rate in the quench significantly affect the final gas composition. Furthermore, depending on the cooling rate in the quench, the hot reactor gas composition prior to the quench could either be preserved (high cooling rate) yielding the same final gas composition after the quench as in the hot reactor or shifted (low cooling rate) towards a higher concentration of H-2 and CO2. (C) 2011 Elsevier Ltd. All rights reserved. 4