This study discusses the combustion behaviours of biogases including different components in an existing conventional natural gas burner. Temperature and emission values have been experimentally measured and investigated on some axial and radial positions by using thermocouples and a flue gas analyzer throughout the combustion chamber. All experiments have been studied for a thermal power of 10 kW and an equivalance ratio of phi = 0.83. The results show that the maximum temperature value was measured and determined to be 1386 K for the biogas flame containing methane up to 65%. This temperature value is high enough and acceptable when it is compared with the methane flame at the same combustion conditions (1467 K). The temperature values of the other biogases are less than that of this biogas temperature values due to containing amount of methane percentage. It can be concluded that the NOX levels (under 25 ppm) of the biogases are less than that of the methane flame because of their low flame temperatures. It can also be demonstrated that the presence of CO2 in the fuels (up to 43 % by volume) leads to a high volume of CO2 emissions in combustion products.