Landfill gas (LFG), having sufficient chemical energy to sustain the operations of commercial combustors, has become a subject of special interest recently. In this study, the flame stabilities of LFG, LFG-mixed fuel I and II were investigated for their applications to domestic appliances using premixed combustion and swirl combustors using non-premixed combustion. LFG-mixed fuel I and II are made by mixing LFG with liquefied propane gas (LPG). LFG-mixed fuel I has higher-heating value (HHV) equivalent to that of liquefied natural gas (LNG), and LFG-mixed fuel II has Wobbe index (WI) equivalent to that of LNG. Thermodynamic calculations and experimental results on burning velocity and flame stability confirmed that LFG-mixed fuel I and II may be used as interchangeable gas of LNG without any modifications of domestic combustion appliance. For the non-premixed type combustor, the flame stability of LFG-mixed fuels is lower than that of LNG in the weak swirl condition. But in the strong swirl condition, the LFG-mixed fuels show similar stable flame zone to that of LNG and thus, can be used as an interchangeable gas of LNG. In addition, LFG itself can also be used as an alternative fuel of LNG, except that the turndown ratio goes down by half. (c) 2006 Elsevier Ltd. All rights reserved.