The ethylene polymerization was catalyzed by the intercalated montmorillonite with the nickel complex, [ArN=C(Me)-C(Me)=NAr]NiBr2 (Ar = 2,6-C6H3 (i-Pr)(2)). Polymer with low melting point and high molecular weight was produced at the early stage of polymerization followed by formation of polymer with high melting point and low molecular weight. It is proposed that the gallery of silicate lowers the propagation rate of polymerization and frequency of "chain walking" process of nickel complex anchored inside the gallery, which produces polymer with low molecular weight and low branching, whereas the nickel complex immobilized on the surface of silicate generates polymer with high molecular weight and high branching. (c) 2005 Wiley Periodicals, Inc.