Abstract The catalytic activity of tetramethylsilylmethyl derivatives of Ti III and T IV compounds in copolymerization of butadiene and propylene has been studied. It is shown that individual Ti IV compounds do not initiate homo- or copolymerization of these monomers in the temperature range of −30°C to +20°C. Alkyl derivatives of Ti III polymerize butadiene, forming polybutadiene-1,2 and are inactive with respect to propylene. In combination with Lewis acids silylmethyl derivatives of Ti III initiate polymerization of propylene and butadiene. The reaction of (CH 3) 3SiCH 2TiCl 3 with C 2H 5Li, and of TiCl 4 with (CH 3) 3SiCH 2Li at low temperatures was studied. It is shown that haloalkyl Ti III derivatives are formed under these conditions, and that the latter initiate copolymerization, including alternating copolymerization, and homopolymerization of butadiene and propylene.