We present here a systematic study on the synthesis of various ZnO nanostructures by electrodeposition method with ZnCl2 solution as starting reactant. Several reaction parameters were examined to develop an optimal procedure for controlling the size, shape, and surface morphology of the nanostructure. The results showed that the morphology of the products can be carefully controlled through adjusting the concentration of the electrolyte. The products present well-aligned nanorod arrays when the concentration is low. However, they act as anomalous hexangular nanoplates when the concentration of ZnCl2 is higher than 5 mM. Transmission electron microscopy and select area electron diffraction results show that the product presents good crystallinity. A possible formation process has been proposed.