AbstractThe new dicationic nickel complex [dppfNi(MeCN)4][BF4]2 (dppf = 1,1′‐bis(diphenylphosphino)ferrocene) in the presence of diethylaluminium chloride (AIEt2CI) exhibited high activity on the 1,3‐butadiene polymerization. Reaction time, temperature and aluminium/nickel molar ratio were optimized in order to achieve maximum activity and selectivity. Conversions higher than 90% were obtained in contrast to other nickel‐based systems using phosphine ligands, the resulting polybutadiene showed high cis‐1,4 (<80%) content and only small amount of 1,2‐units (2%). All polymers presented low molecular weights (Mw > 11 800).