Abstract: The polymerization of butadiene using neodymium catalysts in combination with organomagnesium-organoaluminum complexes has been investigated. About 40% trans-1,4-polybutadiene was obtained when Ph₂Mg was used as one of the catalyst. components Selecting an appropriate formula as well as an order of mixing of components are very important factors for obtaining good yield of high cis-1, 4-polybutadiene.