The effective processing of the C-4 fraction from thermal and catalytic cracking processes is of growing importance for the production of gasoline components and a series of petrochemicals. Besides other processes, the dimerization of n-butene mixtures is currently a subject of research activities, In the review paper the dimerization of n-butenes on amorphous NiO - Al2O3 - SiO2- and nickel zeolite catalysts is discussed under the following points of view: catalysts and their catalytic activity catalytically active phases and sites reaction mechanisms.