thermal degradation of waste plastics in an inert atmosphere has been regarded as a productive method, because this process can convert waste plastics into hydrocarbons that can be used either as fuels or as a source of chemicals. in this work, waste high-density polyethylene (hdpe) plastic was chosen as the material for pyrolysis. a simple pyrolysis reactor system has been used to pyrolyse waste hdpe with the objective of optimizing the liquid product yield at a temperature range of 400oc to 550oc. results of pyrolysis experiments showed that, at a temperature of 450oc and below, the major product of the pyrolysis was oily liquid which became a viscous liquid or waxy solid at temperatures above 475oc. the yield of the liquid fraction obtained increased with the residence time for waste hdpe. the liquid fractions obtained were analyzed for composition using ftir and gc-ms. the physical properties of the pyrolytic oil show the presence of a mixture of different fuel fractions such as gasoline, kerosene and diesel in the oil.