The prime objective of the present study is to explore the basic mechanisms that control and stabilize the biomass combustion, and to study the processes involved in the formation of polluting emissions from the cofiring of wet wood biomass (wood pellets) with premixed swirling propane/ air flame flow. The influence of the cofiring on the chemical/physical changes in the wood pellets, resulting in an ignition and burnout of volatiles, has been investigated for different moisture content in the pellets and different amounts of additional heat supply from the swirling flame flow. The results of the experimental investigations are discussed, describing the effect of the cofiring on the rate of unsteady drying, heating and thermal decomposition of the wet pellets, as well as the ignition and burnout of volatiles that will facilitate the control and optimization of polluting emission composition