Abstract: A process for the production of polybutadiene having a high cis-1,4-content by the polymerization of 1,3-butadiene in an aliphatic solvent in the presence of a catalyst consisting essentially of(a) an organoaluminum compound,(b) water, and(c) a cobalt compound soluble in the aliphatic solvent,is improved by the combination wherein the 1,3-butadiene is polymerized at a temperature of 0.degree.-100.degree. C., the aliphatic solvent is hexane; the catalyst consists essentially of(a) diethylaluminum chloride,(b) water, and(c) cobalt octoate, cobalt naphthenate or a mixture thereof;and the catalyst components are added to a mixture of the 1,3-butadiene and the hydrocarbon solvent in the sequence of (a), then (b), and then (c), wherein the mixture is homogenized after addition of each catalyst component.