In this study, the use of low molecular weight oxidized polyethylenes (OxPE) with different molecular weight and acid number as a new type of compatibilizer in low density polyethylene (LLDPE)/org-clay nanocomposite preparation was examined. Nanocomposites having 5 phr (part per hundred) org-clay were prepared by melt processing. The effect of compatibilizer polarity and clay dispersion on the thermal, mechanical and barrier properties of the nanocomposites was investigated. It was observed that oxidized polyethylenes created a strong interfacial interaction between the clay layers and polymer phase based on the analysis of the linear viscoelastic behavior of the samples by small amplitude oscillatory rheometry. We showed that physical performance of the nanocomposites is not only affected by clay dispersion but also both melt viscosity and polarity of the oxidized polyethylene compatibilizers. It was found that oxygen permeability values of the nanocomposite samples prepared with the oxidized polyethylenes were lower than that of a sample prepared with conventional compatibilizer, maleic anhydride grafted polyethylene (PE-g-MA). © 2007 Elsevier Ltd. All rights reserved.