The present study revealed the effect of different TiO2 nanoparticles employed on catalytic and characteristic properties of LLDPE/TiO2 nanocomposites synthesized by the in situ polymerization with zirconocene/dMMAO catalyst. It was found that the presence of rutile phase in titania apparently resulted in decreased activities due to low intrinsic activity of active sites being present. Based on C-13 NMR results, all LLDPE/TiO2 samples exhibited the random copolymer having different degree of 1-hexene insertion. The highly dispersion of titania can enhance the degree of 1-hexene insertion resulting in decreased crystallinity. (C) 2008 Elsevier B.V. All rights reserved.