Polymerization of ethyl and benzyl diazoacetates (EDA and BDA) initiated with pi-allylPdCl-based systems [pi-allylPdCl/NaBPh4, pi-allylPdCl/NaBAr4F (Ar-F = 3,5-{CF3}(2)C6H3), and pi-allylPdCl] is described. Initiation efficiencies of the pi-allylPdCl-based systems are much higher than those of the previously reported (NHC)Pd/borate (NHC = N-heterocydic carbene) systems, and the new systems are capable of polymerizing the alkyl diazoacetates at low temperatures (0 similar to -20 degrees C), where the (NHC)Pd/borate systems cannot initiate the polymerization. MALDI-TOF-MS analyses of the polymers obtained from EDA provide information for the chain-end structures of the polymers, based on which initiation and termination mechanisms are proposed. Interestingly, EDA polymerization by the pi-allylPdCl-based systems in the presence of alcohols (EtOH, nPrOH, and nBuOH) or water was found to afford RO- or HO-initiated polymers as major products, as confirmed by MALDI-TOF-MS analyses.