(E)-1,3-pentadiene was polymerized at -30 degrees C by using the catalyst system CoCl2((PPrPh2)-Pr-i)(2)-MAO. A trans-1,2-syndiotactic structure was attributed to the semi-crystalline polymer obtained on the basis of the characterization carried out by FTIR, NMR, and WAXD techniques. The thermal behavior of the polypentadiene was investigated by thermogravimetry and differential scanning calorimetry. Isothermal melt crystallization kinetics were analyzed according to the Avrami equation. Nonisothermal crystallization kinetics were elaborated by using Ziabicki and Avrami methods modified by Jeziorny. The equilibrium melting temperature was calculated. The thermal behavior of trans-1,2-syndiotactic polypentadiene was compared with that of 1,2-syndiotactic polybutadiene. (C) 2005 Wiley Periodicals, Inc.