Spherical ZnO nanoparticles were synthesized via a simple one-pot synthesis route by refluxing an oversaturated solution of zinc acetylacetonate hydrate in tert-butanol. A reaction occurs via a ligand-exchange mechanism, i.e., the dissociation of the acetylacetonate group from the zinc center. The formation of ZnO is slow because of the low nucleophilicity, boiling point and dielectric constant of the medium. The single-crystal ZnO nanoparticles develop near the precursor surface until they reach a critical size and, once diffused into the medium, do not agglomerate, but retain their size and morphology. (C) 2011 Elsevier Ltd. All rights reserved.