Current needs for reduced emissions and improved efficiency have motivated the study of the combustion of novel, oxygenated fuels. The scope of the present work is to experimentally and numerically analyse the effect of the addition of three C-2 oxygenated species in rich ethylene flames and to quantify their propensity to inhibit pollutant formation. Acetaldehyde, ethanol and acetic acid are investigated, as representatives of three fuel classes. Novel experimental, speciation results from a low pressure flame configuration are reported. The mechanisms of both research groups co-authoring the study (NTUA and UCL) are analysed. Both appear to satisfactorily reproduce flame structure. The speciation measurements and the reaction path analysis indicate that the performance of oxygenated species with respect to molecular growth is related to their tendency to form ketene and other C-2 species. In this context acetic acid seems to have the least beneficial behaviour towards heavier hydrocarbon formation.