Ethylated and butylated polyethyleneimine ligands were synthesized and employed in copper catalyzed atom transfer radical polymerization of styrene and methyl methacrylate with suitable initiators in order to obtain homogeneous polymerizations, resulting in well defined polymers with low polydispersities. Linear curves drawn from kinetics and conversion - molecular weight plots indicate that all the polymerizations were successfully controlled. In ATRP reactions of S and MMA, the apparent rate of polymerization, k(p)(app), exhibits a plateau at [Ligand]/[CuBr] >= 0.5 ratio for both ligands. The apparent rate constant also decreases by increasing the alkyl chain length of the alkylated polyethyleneimine ligand. Ethylated and butylated polyethyleneimine ligands in ATRP of S and MMA were found to be faster than the existing ATRP ligands. (C) 2010 Elsevier Ltd. All rights reserved.