The development of self-assembled ZnO nanoparticles within a diblock copolymer matrix using wet chemical processing specific to ZnO is reported. Diblock copolymers consisting of polynorbomene and poly(norbomene-dicarboxcylic acid) (NOR/NORCOOH) were synthesized with a block repeat unit ratio of 400 for the first block and 50 for the second block, to obtain spherical microphase separation. The block copolymer self-assembly was used to template the growth of ZnO nanoparticles by introducing a ZnCl2, precursor into the second polymer (NORCOOH) block at room temperature and processing the copolymer by wet chemical methods to substitute the chlorine atoms with oxygen. X-ray photoen-Lission spectroscopy (XPS) verified the conversion of ZnCl2, to ZnO by monitoring the disappearance of the Cl 1s peak and the shift in the binding energy of the Zn 2p(3) peak in the high-resolution spectra. The substitution of Cl by 0 was found to be a highly preferential process, whereby only one approach using a weak base (NH4OH) succeeded in effectively replacing Cl with 0 to result in spherical ZnO nanoparticles having a size ranging from 7 to 15 nm, as determined by transmission electron microscopy. The development of such block copolymer-templated ZnO nanoparticles% is important in enabling the functionalization of large-area nanodevice technologies. (C) 2003 Wiley Periodicals, Inc.