Mixts. of plastics waste and biomass were co-combusted in air in a bubbling fluidized bed reactor (optionally after addn. of liq. petroleum gas to the reactor feed) to det. the rate of its thermal decompn. and flue gas compn. The addn. of liq. petroleum gas resulted in stabilization of the combustion. The combustion of plastics waste particles was faster than that of the biomass particles. A special attention was paid to the dynamics of lighting effects in the system.