The following paper shows an investigation of the distribution of PCDD/F in the flue gas of waste incineration plants. A model, based on the physical adsorption theory, is derived to describe the gas/particle partitionig of the PCDD/F in the flue gas up- and downstream an Activated-Carbon Filter (ACF). In comparison to the theoretical investigation, measurings in the flue gas of waste incineration plants with ACF technologie were performed.