This invention relates to a process for producing an oligomeric product by the oligomerisation of at least one olefinic compound by contacting the at least one olefinic compound with an oligomerisation catalyst in an aliphatic liquid medium at a reaction temperature of at least 50 DEG C. The catalyst comprises the combination of a source of a transition metal; and a ligating compound of the formula (R<1>)m X<1> (Y) X<2 >(R<2>)n.