Polyethylene/clay (PE/Clay) nanocomposites were prepared by the in situ polymerization of ethylene using the new Clay/butyl octyl magnesium (BOM)/Chloroform/EtOH/TiCl4/tri ethyl aluminum (TEA) catalyst system in heptane where BOM and TEA were the support for the clay modification and cocatalyst, respectively. The influence of the modified clay using BOM on the catalyst and polymerization was investigated. Also, the effect of temperature, pressure, hydrogen, and the molar ratios of TEA/Ti on the catalyst yield and ethylene consumption (polymerization rate) were studied. It was found that the above clay-supported catalyst was an efficient ZieglerNatta type catalyst due to its suitable yield for the polymerization of ethylene toward the production of the PE/Clay nanocomposites. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013