Studies were carried out to evaluate the influence of microwave (MW) pre-treatment of different lignocellulosic biomass pellets (wood, wheat straw and peat) on the development of combustion characteristics of pre-treated pellets. Biomass pellets were MW pretreated using a 700 W power microwave oven by varying the MW irradiation time of biomass pellets along with estimation of the effect of MW pre-treatment on the development of flow dynamics, flame temperature, produced heat energy and composition of emissions. Experimental studies were conducted using a laboratory-scale setup with 5 kW power, which combines a biomass gasifier and a combustor. Results of the complex research show that the MW pre-pretreatment of biomass pellets activates the formation of combustible volatiles intensifying their ignition and combustion, increasing thus the generated heat power and the produced heat energy per mass of activated pellets. A noteworthy result is that the combustion efficiency and the composition of emissions are improved.