The emissions of polychlorinated-p-dibenzodioxins (PCDD) and dibenzofurans (PCDF) from waste combustion show a close correlation with the emissions of chlorinated benzenes or phenols, which could therefore be used as indicators for easier. faster and cheaper prediction of the potential dioxin emission levels. Using contemporary analytical methods. the emissions of. e.g. monochlombrenzene can be measured on-line and predictions could be made via a suitable mathematical model describing the link between these precursors and dioxins. Modeling the formation of the precursors could therefore provide an indirect possibility for the prediction of dioxins' formation and optimization of the combustion process characteristics. A detailed combustion mechanism consisting of 3678 gas-phase reactions between 755 species including chlorine chemistry has been developed. The influence of temperature, reaction time, equivalence ratio and chlorine concentration on monochlorobenzene and monochlorophenols formation was tested for batch and well-stirred reactors. The impact of good mixing conditions. appropriate level of oxygen, chlorine contents and temperature regime on the formation of precursors of dioxins is emphasized. (C) 2004 Elsevier Ltd. All rights reserved.