Selective desulphurization and denitrogenation of hydrocarbon mixtures rich in olefins (FCC-, pyrolysis- and coker naphtha) were investigated over three different catalysts (conventional and new generation CoMo/Al(2)O(3), Pt(0.1%) Pd(0.3%)/USY). According to the experiments carried out in a wide range of operation parameters it was concluded that the sulphur removal efficiency of the PtPd/USY approximately equals to that of the new generation CoMo/Al(2)O(3) up to about 200 mg/kg sulphur and 35 mg/kg nitrogen content, but the octane number loss is lower and the nitrogen removing efficiency is significantly better (nearly 100%) as well, than in case of the previous catalyst. In case of feedstock having higher sulphur and nitrogen content, the utilisation of CoMo/Al(2)O(3) together with PtPd/USY in one reactor enables the production of very low sulphur (<5 mg/kg) and nitrogen (<2 mg/kg) containing products with low octane number loss. (C) 2011 Elsevier B.V. All rights reserved.