The authors experimentally studied the formation of submicron particles from a domestic gas cooker in a compartment free from external particle sources. The effects of fuel (methane, natural gas, odorant-free natural gas), primary aeration, flow rate, and fuel sulphur content on particle emissions were investigated. The experiments confirmed reports from literature that blue burning flames of domestic gas cookers emit submicron particles. The particle number concentrations varied in the range 103-106particles/cm3, depending on the fuel, flow rate, and primary air addition. The diameters of the emitted particles were found to have a mean value of about 7nm for partially premixed flames, increasing to 10nm for nonpremixed flames. The quantity of primary air had a strong impact on the particle emissions, showing a minimum at a primary aeration level of 60-65%. Presence of sulphur in small quantities may enhance particle formation under some conditions, but results were not conclusive.