Abstract: Cis-1,4-polybutadiene rubber with vinyl content ranging from 7 to 16% in a form of syndiotactic-1,2-polybutadiene blocks was synthesized with cobalt catalyst systems through two-stage polymerization. The po-lymer obtained has been characterized by their solubility behavior, infra-red spectrum, X-ray diffraction patterns, incipient crystallization tempera-ture and half crystallization time.