The rheology of linear and branched metallocene polyethylenes (m-PEs) was investigated. The linear metallocenes were prepared by gas-phase polymerization, while the branched PEs were commercial resins. Molecular parameters such as M-w, branch type, and molecular weight distribution have influenced the viscoelastic behavior of both linear and branched PEs, whereas branch content (BC) had little influence on viscoelastic properties. Plots of log G' versus log G" revealed the effect of comonorner type on the viscoelastic behavior of m-PEs. Flow activation energy (E) was found to be sensitive to both M-w and BC. Also, E for ethylene-octene copolymers was observed to be always higher than the butene counterparts, which have been caused by the increase in molar volume of the repeating unit. For the effect of BC on E, different trends were observed for octene and butene m-LLDPEs. (c) 2006 Wiley Periodicals, Inc.