The tris[(4-dimethylaminopyridyl)methyl] amine (TpmA(Nme2)) as a ligand for copper-catalyzed atom transfer radical polymerization (ATRP) is reported. In solution, the [Cul(TPMA(Nme2))Br] complex shows fluxionality by variable-temperature NMR, indicating rapid ligand exchange. In the solid state, the [Cu-I(TpmA(Nme2))Br][Br] complex exhibits a slightly distorted trigonal bipyramidal geometry (tau = 0.89). The UV-vis spectrum of [Cuu(TpmA(Nme2))Bd+ salts is similar to those of other pyridine-based ATRP catalysts. Electrochemical studies of [Cu(TPMA(Nme2))](2+) and [Cu(TPMA(NMe2))Br](+) showed highly negative redox potentials (E-1/2 = -302 and -554 mV vs SCE, respectively), suggesting unprecedented ATRP catalytic activity. Cyclic voltammetry (CV) in the presence of methyl 2-bromopropionate (MBrP; acrylate mimic) was used to determine activation rate constant k(a) = 1.1 X 106 M-1 s(-1), confirming the extremely high catalyst reactivity. In the presence of the more active ethyl alpha-bromoisobutyrate (EBiB; methacrylate mimic), total catalysis was observed and an activation rate constant ka = 7.2 X 10(6) M-1 s(-1) was calculated with values of K-ATRp approximate to 1. ATRP of methyl acrylate showed a well-controlled polymerization using as little as 10 ppm of catalyst relative to monomer, while side reactions such as Cul-catalyzed radical termination (CRT) could be suppressed due to the low concentration of L/Cu-I at a steady state.