A process for the preparation of ethylene α-olefin copolymers by copolymerizing ethylene with α-olefins in the presence of a catalyst formed by contacting a metallocene complex with a cocatalyst, wherein the metallocene complex is a metallocene complex according to formula I or a metallocene complex according to formula II, wherein M is chosen from the group of Ti, Zr and Hf; Q is halogen (F, Cl, Br, I) or an alkyl group comprising 1 to 20 carbon atoms; k is the number of Q groups, is an integer and equals the valence of M minus 2; and wherein R1, R2, R3 and R4 are identical or different and can be chosen from alkyl groups with 1-20 carbon atoms.