This paper presents the experimental results of MSW gasification in a spout-fluid bed reactor. Municipal solid waste (MSW) modeled based on compositions of Bangkok waste transfer station "On-nuch" was used as the fuel. Three scenarios were investigated in this study. in the base case scenario, only primary air of equivalence ratios (ER) 0.35, 0.3, 0.25, 0.2, and 0.15 were used. The other two scenarios investigated the influence of secondary air in the free board, and the effect of the recirculation of carryover captured by the cyclone inside the reactor's free board at an ER of 0.25. In the base case, higher heating values of 2.40-5.05 MJ/Nm(3) were obtained with the ER values of 0.35-0.15, respectively. However, opposite trend was observed for the tar content. At ER of 0.35, a value of 11.37 g/Nm(3) was found compared to 20.76 g/Nm(3) at ER of 0.15. The tar content in the producer gas was reduced from 14.47 to 10.98 g/Nm(3) when secondary air was supplied in the freeboard due to an increase in temperature. The gasification efficiency was increased from the base case which was 35.78 to 38.99% with the recirculation of carryover. Higher heating value of producer gas was found to be 4.4-4.9 MJ/Nm(3) in this case. (C) 2008 Elsevier B.V. All rights reserved.