The star-block copolymers poly(styrene)-block-poly(4-vinylpyridine) ((PS-b-P4VP)(4)) are synthesized by two-step atom transfer radical polymerization (ATRP) using pentaerythritol tetrakis (2-bromoisobutyrate) as initiator. The star-block copolymers form reverse micelles in toluene with the P4VP core and the PS shell. The reverse micelles and their complexes with HAuCl(4)(.)3H(2)O are investigated by a combination of dynamic laser scattering (DLS) and static laser scattering (SLS) in toluene. Gold nanoparticles are subsequently obtained by reducing the complex micelles with anhydrous hydrazine. The size and morphology of reverse micelles, hybrid micelles and gold nanoparticles are also investigated by transmission electron microscope (TEM). The obtained gold nanopanicles are of small quantum size (ca. 2 nm) and narrow distribution. (c) 2006 Elsevier Ltd. All rights reserved.