Copolymerizations of ethylene with 1-decene were carried out with a series of stereospecific metallocene compounds, rac-(EBI)Zr(NMe2)(2) [1, EBI = ethylene-1,2-bis(1-indenyl)], rac-(EBI)Hf(NMe2)(2) (2), rac-Me2Si(1-C5H2-2-Me-4-Bu-t)(2)Zr(NMe2)(2) (3), ethylidene(cyclopentadienyl)(9-fluorenyl)ZrMe2 [4, Et(Flu)(Cp)ZrMe2] and isopropylidene(cyclopentadienyl)(9-fluorenyl)ZrMe2 [5, iPr(Flu)(Cp)ZrMe2], combined with Al(i-Bu)(3)/[CPh3] [B(C6F5)(4)] cocatalyst. All catalyst systems showed very high copolymerization rates and the 1-decene reactivity decreased in the order of 2 > 5 > 1similar to 4 > 3. The reactivity product of ethylene and 1-decene (r(E) x r(D)) was below 1 except 3 catalyst, corresponding to random copolymer structures with an alternating character. The melting point (T-m), crystallinity (X-C), intrinsic viscosity ([eta] and density of the 1-decene/ethylene copolymers decreased markedly with an increase in the 1-decene content, regardless of the type of catalytic system.