The oligomerisation of ethylene to linear alpha olefins is an important industrial process for the production of polyethylene co-monomers, plasticizers, surfactants and waxes. With the ever increasing market demand for short chain linear alpha olefins (1-butene, 1-hexene and 1-octene) there has been intensive research in both industry and academia on methods to selectively oligomerise ethylene to form only the short chain fractions. As such, a range of novel catalysts based on titanium and chromium have been synthesised and characterised. Their behaviour in ethylene oligomerisation and polymerisation has been studied. In most cases, the mechanism of oligomer formation has been investigated.