The purpose of this study was to investigate gasification performance of four switchgrass pretreatments (torrefaction at 230 and 270 degrees C, densification, and combined torrefaction and densification) and three gasification temperatures (700, 800 and 900 degrees C). Gasification was performed in a fixed-bed externally heated reactor with air as an oxidizing agent. Switchgrass pretreatment and gasification temperature had significant effects on gasification performance such as gas yields, syngas lower heating value (LHV), and carbon conversion and cold gas efficiencies. With an increase in the gasification temperature, yields of H-2 and CO, syngas LHV, and gasifier efficiencies increased whereas CH4, CO2 and N-2 yields decreased. Among all switchgrass pretreatments, gasification performance of switchgrass with combined torrefaction and densification was the best followed by that of densified, raw and torrefied switchgrass. Gasification of combined torrefied and densified switchgrass resulted in the highest yields of H-2 (0.03 kg/ kg biomass) and CO (0.72 kg/kg biomass), highest syngas LHV (5.08 MJ m(-3)), CCE (92.53%), and CGE (68.40%) at the gasification temperature of 900 degrees C. (C) 2014 Elsevier Ltd. All rights reserved.