A process for improving the quality of a crude pyrolysis oil originating from a pyrolysis of plastic waste is provided, the process comprising providing a crude pyrolysis oil originating from the pyrolysis of plastic waste, adjusting the pH value of the crude pyrolysis oil, resulting in a pretreated crude pyrolysis oil, performing a solid-liquid-separation of solid components and liquid components of the pretreated crude pyrolysis oil and/or subjecting the pretreated crude pyrolysis oil to a liquid-liquid-separation.