(EN) A process for the tetramerisation of ethylene under solution phase conditions is carried out in the presence of an activated catalyst at a temperature above 80°C and up to a temperature of about 130°C. The activated catalyst is provided by combining a source of chromium a ligating compound which ligating compound includes at least one fluorine substituted hydrocarbyl group organoheteryl group or heterohydrocarbyl group and optionally a catalyst activator or combination of catalyst activators.
