Hydrolysis of 4-nitrophenyl benzoate (PNPB) in the presence of ionene nanoreactors was studied comparing the ionenes, poly[(dimethyl)-2-hydroxy propanodiyl chloride] (2-OH-33R1), poly[(methylbutyliminium)-2-hydroxy propanodiyl chloride] (2-OH-33R4) and poly[(methyloctyliminium)-2-hydroxy propanodiyl chloride] (2-OH-33R8). Methyl orange incorporation and study of viscosity showed that increase of the side chain length of the ionene enhances the ability to form globular hydrophobic microdomains. Catalytic hydrolysis of PNPB follows the order 2-OH-33R8 >> 2-OH-33R4 > 2-OH-33R1, and 2-OH-33R8 has the lowest pK(a) that may reflect its higher hydrophobicity, which apparently influences the ionene nanoreactor reactivity. A lower pK(a) indicates easier deprotonation of the alkoxide group, which participates more effectively in the reaction and the 2-OH-33R8 functionalized ionene acts as a specially effective catalytic homogeneous nanoreactor. (C) 2010 Elsevier B.V. All rights reserved.