1,3-Octadiene, 1,3-heptadiene, and 5-methyl-1,3-hexadiene were polymerized with the catalytic systems AlEt2Cl-Nd(OCOC7H15)(3)-Al(Bu-i(3)), CoCl2((PBu2Me)-Bu-t)(2)-MAO, and CoCl2((PPrPh2)-Pr-i)(2)-MAO, obtaining novel stereoregular polymers, never reported before, having isotactic cis-1,4, syndiotactic cis-1,4, and syndiotactic trans-1,2 structures, respectively. The polymers were characterized by IR, NMR (H-1, C-13, and 2D experiments), DSC, GPC, and WAXD analyses. The polymer structures obtained confirm and support once more what was already reported concerning the strong influence of catalyst and monomer structures on regio- and stereoselectivity in the polymerization of 1,3-dienes. (C) 2013 Elsevier Ltd. All rights reserved.