In the present paper, the results of 1-hexene oligomerization in the presence of recyclable chloroaluminate type ionic-liquid catalysts and their combination with Ti-containing complexes with "grafted ionic-liquid" type ligands are reported. The possibility of selective preparation of products with predominantly (similar to 70%) oligoalkylnaphthenic structure and narrow molecular weight distribution (M-w/M-n = 1.03-1.55) is shown. The regulation of molecular weights of oligomer products is achieved by changing the molar ratio of the catalytic system components. The mechanism of selective formation of oligoalkylnaphthenic hydrocarbons by oligocyclization of alpha-olefins in the presence of ionic-liquid catalysts is suggested. The term of oligocyclization is used to indicate consecutive reactions of oligomerization and cyclization, mediated by the same catalytic center or catalyst. The oils obtained are qualified as the novel class of synthetic oils, namely as the class of synthetic oligoalkylnaphthenic oils. (C) 2009 Elsevier B.V. All rights reserved.