In this paper the gasification of sawdust in an air cyclone gasifier was investigated to produce a high quality fuel gas with less tar. The effect of air to fuel ratio on the gasification characteristics was studied. The results indicate that as the air to fuel ratio varying from 0.23 to 0.35, the lower heating value of the produced gas is 4.5-5.7 MJ/Nm(3), the carbon conversion is 77.0-94.2%, the cold gas efficiency of the gasification system is 53.6-63.0%, while the tar content is 4.4-8.4 g/Nm(3). A detailed CFD model of a cyclone gasifier has been developed, based on the Fluent package. Models of sawdust pyrolysis and combustion of volatiles and char have been added to the standard model. The model provides information on the gas temperature in the gasifier and the composition of the outlet gas. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.