This paper presents numerical results on the performance characteristics of a swirl burner operating with partially premixed LPG-air jet flames. Commercial CFD code FLUENT is used to analyse the effect of partial premixing of fuel jet with air on NOx, CO2 and CO emissions. For a given combustion-air swirl intensity, the fuel-jet percentage primary aeration (%PA) is varied from zero to 45% for the burner operating with 1.0 m3/h of fuel flow rate and stoichiometric amount of swirl-air. The results obtained show that NOx level increases with % PA and reaches a constant maximum value over %PA from 35 to 45%. The CO level also increases gradually, reaches a maximum and then decreases to reach a plateau. These observations suggest that NOx and CO emissions can be controlled optimally by adjusting partial premixing of the fuel jet. © 2009 Combustion Institute. All rights reserved.