The amount of oxygen in air has been changed and the effect of oxygen amount has been numerically investigated on combustion and emission parameters of coke oven and generator gases in a model combustor. A CFD code has been used to perform numerical analysis. Combustion has been modelled by using the PDF/Mixture Fraction combustion model, standard k-epsilon turbulence model as turbulence model and P-1 radiation model as radiation model. The amount of oxygen in the air has been changed from 21 % to 30 %, 40 % and 50 %. According to the predictions, it can be readily said that the flame temperatures of the coke oven and the town gases increases under oxygen-enriched combustion conditions. Therefore, it is demonstrated that the combustion performances of the coke oven and town gases have been improved under oxygen-enriched combustion. When the results are evaluated in terms of emissions, it has been determined that CO emissions decrease while CO2 emissions increase as the air is enriched with oxygen. It has been also concluded that NOX emission levels increase under oxygen-enriched combustion conditions due to increases in flame temperatures of the coke oven and the town gases. The maximum flame temperature level has been predicted as of almost 2200 K under % O2-included air conditions just as the maximum NOX level has been also predicted as about 1500 ppm under the same conditions.