In this study, the conversion of HDPE in VGO to fuels was carried out in absence and presence of catalyst. The blend containing 20% HDPE was co-processed in presence of hydrogen at the temperatures of 435 and 450degreesC. Five kinds of metal supported on active carbon catalysts (M-Ac) and acidic catalysts (HZSM-5 and DHC-8) were tested. The product distribution and the quality of liquid product changed depending upon the temperature and the type of catalyst. Among the metal supported active carbon catalyst, Co-Ac showed the highest cracking activity where as Mo-Ac showed the highest hydrodesulfurization activity. Co-Ac had better cracking activity than commercial hydrocracking catalyst (DHC-8). Although HZSM-5 had the best cracking effect in the hydrocracking of HDPE/VGO blend, the liquid product from HZSM-5 contained the highest sulphur. The use of carbon-supported metal catalysts in the co-processing of HDPE with VGO looks promising solution from an environmental viewpoint. (C) 2002 Elsevier Science B.V. All rights reserved.