To determine the emission factors of biofuel-burning cooking devices by means of the ＇chamber＇ method (the determination of emission source strength from a mass rate balance within a dilution chamber) it is necessary to assume constant pollutant emission rates. Simulated and measured emission factors for two cooking devices were used to assess the impact of the refuelling schedule and the chamber air exchange rate on accuracy. It was found that better accuracy with the method is obtained with refuelled cooking devices since this leads to a more constant emission rate. Thus cooking devices should be refuelled regularly and not operated with a single charge of fuel as was suggested in earlier studies using the chamber method. Of the two methods compared for calculating emission factors from data collected in chamber tests the accuracy of the least squares method deteriorates with increasing air exchange rate and that of the simple mean method improves. The simple mean method of calculating emission factors gave better results than the least squares method and should therefore be used. A comparison between tests conducted at differing air exchange rates is problematic. The open fares are favoured by the chamber method since emission rates are more close to constant than for the other cooking devices considered. Further study and discussion appear to be necessary before the method can be recommended to development organisations for use in comparing emissions from cooking devices.