A fuel-lean reburn system is found here to be able to replace a conventional reburning technique in terms of increasing efficiency. In the fuel-lean reburn system, the amount of injected reburn fuel into the reburning zone is low enough to maintain the overall fuel-lean condition in the furnace, so that no additional air system is required, and CO emission can be maintained at almost zero level. In this study, an experimental study has been done to examine the reduction characteristics of NOX in a lab scale combustor (15 kW) with various oxygen-enhanced combustion conditions. Liquefied Petroleum Gas (LPG) was used as a main fuel and reburn fuel. Finally, the current fuel-lean reburn system, even with only an amount of reburn fuel of 13% of total heat input, was observed to achieve a maximum of 48% in NOX reduction. Copyright (C) 2010 John Wiley & Sons, Ltd.