A review with 81 refs. covering studies on catalyzed cyclotrimerization of 1,3-butadiene (BD), applications of the resulting isomeric 1,5,9-cyclododecatriene (CDT) products, cyclotrimerization chemistry including side reactions (temp., solvent type), catalyst systems (mole ratio of system components, modifiers and additives), and fundamental process parameters. Flowsheets are shown of commercial process for making CDT, 1,5-cyclooctadiene (COD) and cyclododecane (CDA). Separation of crude CDT reaction mixture products is described in more detail.