Ozone is considered an environmentally friendly alternative for currently applied H2SO4-based mixtures in the cleaning of semiconductor devices. In order to implement ozone/water cleaning processes in practical systems, fundamental research is needed to understand the underlying chemical processes. Related to the removal of organic contamination from silicon surfaces, one needs to know whether ozone or radical species are the most efficient. A kinetic modeling study is performed to solve this problem whereby the pH is varied and different additives are checked. Theoretical concepts as Dominant Oxidation Pathway (DOP) and Radical Pool (RP) will be introduced for the evaluation of the various reaction pathways.