AbstractA two‐component organometallic catalyst of composition CH3TiCl3·CH3AlCl2effects high‐speed polymerization of ethylene in the presence of chlorinated hydrocarbons at low temperatures. The catalyst does not undergo any alteration in the process. In contrast to the Ziegler catalysts, the titanium remains quadrivalent. Olefins of low‐molecular‐weight and with branched structures are produced. It proved possible to isolate the primary products of the polymerization at −50 to −100°C and to elucidate the mode of their formation from a knowledge of their structures. The findings are incompatible with either a cationic or anionic reaction mechanism. A novel type of mechanism is proposed, whereby the catalyst is supposed to have an ionic structure and molecular growth proceeds via π‐complex formation of the olefin with the titanium cation. The formation of ethylene/olefin copolymers i