Balancing measurements of PCDD/F in the flue gas cleaning system in the municipal waste incineration test plant TAMARA were described. Additionally, materials applied in wet scrubbing systems were investigated. The observed change of the PCDD/F pattern and values in the flue gas passing the wet scrubbing system can be explained with a PCDD/F-absorption/desorption equilibrium of the wall material, All investigated technical plastics show a strong, temperature-dependent PCDD/F absorption/desorption behavior.