The POP's are present as trace compounds in the atmosphere and they are subject of increasing environmental concern. Some of them are due to the incomplete combustion in the municipal solid waste incinerator and can be rejected by the chimney. The main process used to eliminate the POP's from gas stream is the adsorption on activated materials. In this study, two POP's were tested: fluoranthene and hexachlorobenzene (HCB). The retention mechanism on the activated materials tested (powdered activated carbon and coke) seems to be an adsorption followed by a catalytic reaction on the surface. The effect of the temperature parameter was found to be favorable to the retention of the pollutants. This can be explained only by a catalytic reaction. Other experimental parameters such as humidity, nature of the gas phase (O-2, N-2, CO2, etc.) was studied. The competition phenomena, when the two POP's are present, were also approached. A synergy between the reaction mechanisms probably occurs under these conditions. Finally a statistical study made it possible to highlight the influence of the experimental parameters such as temperature, nature of the gas phase and humidity. (c) 2007 Elsevier B.V. All rights reserved.