The anionic polymerization of (E)-1,3-pentadiene (EP) and (Z)-1,3-pentadiene (ZP) together with mixture of the E/Z isomers are investigated, respectively. The kinetic analysis shows that the activation energy for EP (86.17 kJ/mol) is much higher than that for ZP (59.03 kJ/mol). GPC shows that it is the EP rather than the ZP isomer that undergoes anionic living polymerization affording quantitative products of the polymers with well-controlled molecular weights and narrow molecular weight distributions (1.05 <= D <= 1.09). In addition, THF as polar additive has proved its validity to reduce the molecular weight distribution of poly(ZP) from 1.38 to as low as 1.19. The micro-structure and sequence distributions of polypentadiene are characterized by H-1 NMR and quantitative C-13 NMR. Finally, the distinctive reaction activity of two isomers can be elucidated by two different mechanisms which involve the presence of four forms of zwitterions for EP and the typical [1,5]-sigmatropic hydrogen-shift phenomenon for ZP. (C) 2016 Wiley Periodicals, Inc.