A process for production of higher linear alpha olefins and/or alkyl-branched
alpha
olefins, which comprises the co-oligomerisation of one or more alpha olefins with
ethylene in the presence of a metal catalyst system employing one or more bis-aryliminepyridine
MXa complexes and/or one or more [bis-aryliminepyridine MYp.Lb+][NC-]q
complexes; and said process is carried out at an ethylene pressure of less
than 2.5 MPa.