The combustion difficulties for low heating value (LHV) gases derived from biomass fuels via a gasification process have led to more investigations into LHV gas combustors. Cyclone combustors provide good air/fuel mixing with long residence times. In this study, a small-scale pressurized cyclone combustor (PCC) was designed and optimized using computational fluid dynamics (CFD) simulation. The PCC, along with a turbocharger-based, two-stage microturbine engine, was first characterized experimentally with liquefied petroleum gas (LPG) fuel and then with both LPG and LHV gas derived from biomass in dual-fuel mode. The combustor achieved ultra-low CO and NO(x) emissions of about 5 and 7 ppm, respectively, for LPG fuel and of about 55 and 12 ppm, respectively, in dual-fuel mode at the maximum second-stage turbine speed of 26,000 rpm with stable turbine operation. (C) 2010 Elsevier Ltd. All rights reserved.