The catalytic degradation of high-density polyethylene was conducted in a reactive extruder at reaction temperatures of 425, 450, and 475 degrees C using silica-alumina as the cracking catalyst. A continuous kinetic model was proposed and compared to the carbon number distribution of the reaction products. The model prediction of the product selectivity described the experimental data well for a reaction temperature of 425 degrees C; however, it was. too simplistic to predict the decrease in C-4 and increase in C-3 occurring at higher reaction temperatures. The liquid product obtained from the reactive extruder was comparable to gasoline; however, it did show a significantly higher C-5 fraction.