Living radical polymerization of n-butyl acrylate was achieved by single electron transfer/degenerative-chain transfer mediated living radical polymerization in water catalyzed by sodium dithionate. The plots of number-average molecular weight versus conversion and ln[M](0)/[M] versus time are linear, indicating a controlled polymerization. This methodology leads to the preparation of alpha,omega-di(iodo) poly (butyl acrylate) (alpha,omega-di(iodo)PBA) macroinitiators. The influence of polymerization degree ([monomer]/[initiator]), amount of catalyst, concentration of suspending agents and temperature were studied. The molecular weight distributions were determined using a combination of three detectors (TriSEC): right-angle light scattering (FALLS), a differential viscometer (DV), and refractive index (111). The methodology studied in this work represents a possible route to prepare well-tailored macromolecules made of butyl acrylate in an environmental friendly reaction medium. Moreover, such materials can be subsequently functionalized leading to the formation of different block copolymers of composition ABA. (c) 2006 Wiley Periodicals, Inc.