To obtain basic knowledge on degradation of polyethylene (PE) to oils in supercritical water, effects of reaction temperature, reaction time, water/PE ratio and water filling rate on degradation of PE to oils were investigated in supercritical water with a 125-ml autoclave. Reaction conditions were in the range of temperature 450-480 degreesC, time 1-30 min, water/PE ratio 2/1-10/land water filling rate 25-40%. The experimental results showed that the yield of oil was decreased with an increase of temperature and extension of reaction time, while yield of gas was increased. H2O/PE ratio not only affected the yield of products, but also changed the composition of oil products. From increasing productivity of unit volume of reactor, H2O/PE ratio of 2-4 was reasonable. The effect of water filling rate on oil yield was not significant. The oil yield of degradation of PE to oils was more than 90 wt.% under reaction temperature of 460 degreesC, reaction time of 1 min and water/PE ratio of 6. It provided the basic data for development of a process of continuous degradation of PE to oils. (C) 2004 Elsevier B.V. All rights reserved.