Cenospheres (300 g, 25-300 mu m grain size) and air (30 L/min) were used in a fluidized bed reactor (96 mm diam., 500 mm length) for sep. utilization of 3 polyethylene and 2 polypropylene types at temp. 450-650 degrees C. IR spectroscopy with Fourier transformation was used to det. the content of CO, CO2 and the sum of org. compds. in the exhaust gas for each type of raw material. The CO2 was the dominant component of the exhaust gas generated from polyethylene, regardless of the process temp. and polyethylene type. The polypropylene combustion at 450 degrees C resulted in the formation of combustion gases with a dominant content of org. compds. (but depending on the polypropylene type) which decreased with increasing temp.