The copolymerization of ethylene with dicyclopentadiene ( DCP ) in the presence of a constrained geometry tetramethylcyclopentadi-enyl-phenoxytitanium catalyst [ 2,4 -t Bu2 -6 - ( 2,3,4,5 -Me4 -Cp ) -PhO ] TiCl2, combined with Al( iBu)3/Ph3C+ B( C6F5 )-4 cocatalyst system was studied. The copolymers that were formed were characterized by 1H and 13C NMR, differential scanning calorimetry (DSC), SEM, and X-ray diffraction (XRD) analyses. The results of the analysis indicate that the copolymers of ethylene with dicyclopentadiene are amorphous and display two or more melting temperatures in their DSC diagams. Moreover, the morphologies of the copolymers are quite different from that of polyethylenes.