This invention relates to the oligomerisation of olefinic compounds in the presence of an activated oligomerisation catalyst. The invention also extends to a particular manner for providing an activated oligomerisation catalyst. According to the the present invention, there is provided a process for producing an oligomeric product by the oligomerisation of at least one olefinic compound, the process including (a) providing an activated oligomerisation catalyst by combining, in any order, iii) a source of chromium, ιv) a ligating compound of the formula (R
1 )m X
1 (Y) X
2 (R
2 )n wherein X
1 and X
2 are independently an atom selected from the group consisting of nitrogen, phosphorus, arsenic, antimony, bismuth, oxygen, sulphur and selenium or said atom oxidized by S, Se, N or O where the valence of X
1 and/or X
2 allows for such oxidation, Y is a linking group between X
1 and X
2 which linking group contains at least one nitrogen atom which is directly bonded to X
1 or X
2 , m and n are independently 0, 1 or a larger integer, and R
1 and R
2 are independently hydrogen, a hydrocarbyl group, an organoheteryl group or a heterohydrocarbyl group, and the respective R
1 groups are the same or different when m>1, and the respective R
2 groups are the same or different when n>1, in) a catalyst activator which is an organoboron compound including a cation and a non-coordinating anion of the general formula [(R
10 )x L* - H]+ [B(R
20 )4]
- wherein L* is an atom selected from the group consisting of N, S and P, the cation [(R
10 )x L* - H]* is a Bronsted acid, x is an integer 1, 2 or 3, each R
10 is the same or different when x is 2 or 3 and each is a -H, hydrocarbyl group or a heterohydrocarbyl group, provided that at least one of R
10 comprises at least 6 carbon atoms and provided further that the total number of carbon atoms in (R
10 )x collectively is greater than 12, R
20 independently at each occurrence is selected from the group consisting of hydride, dialkylamido, halide, alkoxide, aryloxide, hydrocarbyl, halosubstituted-hydrocarbyl radicals, halosubstituted-alkoxide, halosubstituted-aryloxide and a halosubstituted aromatic ring moiety with at least one halide substituent on the aromatic ring, and vi) an aliphatic solvent, and (b) contacting the at least one olefinic compound with the activated oligomerisation catalyst to produce an oligomeric product.