Three new partially-aerated burners have been developed for Australian cooktops fired with natural gas, with maximum thermal inputs of 12, 7.5 and 5.5 MJ h(-1). These novel burner designs minimise the NO2 emission per unit of useful energy, since NO2 is the more toxic nitrogen oxide of concern for indoor air pollution. They provide lower values of the ratio of NO2 emission to thermal efficiency than production burners, with respective reductions of 42, 13 and 23% compared with production burners of corresponding size. The traditional combustion diagrams of these prototype burners have been defined, on plots of primary aeration Versus thermal input, to identify the regions of stable flame operation. However, the regions of satisfactory operation are further limited at low primary aeration by the Australian Gas Association requirement for CO/CO2 ratio <0.01 and at low thermal inputs by the requirement for re-ignition after exposure to a standard draught of 5 km h(-1). To achieve the full emission reduction potential of these burners, the air-gas supply system needs to be re-designed to increase the primary aeration at the maximum thermal input to similar to 62%, from the similar to 50% achieved by production air-gas supply systems. The required turndown of 5:1 can be achieved by these prototype burners, provided the operating curves of primary air/gas ratio versus thermal input for the re-designed air/gas systems lie within the regions of stable and satisfactory flame operation defined on the combustion diagrams.