The degradation of four different types of polyethylene (PE) namely high density PE (HDPE), low density PE (LDPE), linear low density PE (LLDPE), and cross-linked PE (XLPE) was carried out at 430°C by batch operation using silica-alumina as a solid acid catalyst and thermally without any catalyst. For thermal degradation, both HDPE and XLPE produced a significant amount of wax-like compounds and the yields of liquid products (58-63 wt%) were lower than that of LDPE and LLDPE (76-77 wt%). LDPE and LLDPE produced a very small amount of wax-like compounds. Thus the structure of the degrading polymers influenced the product yields. The liquid products from thermal degradation were broadly distributed in the carbon fraction of n-C5 to n-C25 (boiling point range, 36-405°C). With silica-alumina, all of the polyethylenes were converted to liquid products with high yields (77-83 wt%) and without any wax production. The liquid products were distributed in the range of n-C5 to n-C20 (mostly C5-C12). A solid acid catalyst indiscriminately degraded the various types of polyethylene into light fuel oil with an improved rate. © 1997 Elsevier Science Limited. All rights reserved.