Hexagonal-shaped nanoprisms of ZnO on indium tin oxide substrates are grown using an electrochemical process. The surface morphology and crystallinity of the ZnO nanostructures are characterized by field-emission scanning electron microscopy and X-ray diffraction, respectively. Perfectly hexagonal-shaped ZnO nanoprisms can be obtained by varying the current density and potential. On increasing the current density, initial nucleation of isolated and uniform nanoprisms are achieved at a certain current density. The bandgap energy of the ZnO nanoprisms calculated from optical data is found to be 3.308 eV. Photoluminescence data at low temperatures demonstrate a high optical quality of these structures, with intense excitonic peaks. A high-energy excitonic emission at 3.387 eV is observed at 10 K, close to the bandedge emission, which is due to the A-exciton in ZnO nanostructures. (C) 2008 The Electrochemical Society.