In this study, a CFD model was developed to predict NOx emissions, temperatures and species mole fractions in a Mild combustion experimental burner which was fed with hydrogen and hydrogen/CO2/H2O mixtures. Numerical simulations are performed with three turbulence models, three combustion models and two kinetic mechanisms. The temperature and flow fields data are exported to KPP numerical tool for prediction of NOx. It was found that the KPP and CFD results are in good agreement with experimental observations only when the RSM-transition turbulence model together with modified EDC and POLIMI 1101 syngas mechanism are employed in the model.