The paper deals with electrosynthesis of zinc oxide nanostructures under controlled mass transfer rate. The results of this works show that mass transfer is a main factor to control and change the morphology of zinc oxide nanostructures from the nanosheets to the nanoparticles. Electrosynthesis was done by direct oxidation of zinc anode by exerting pulsed current in the solution containing sodium sulfate and sodium sulfide. At diffusion mass transfer (DMT) control zone, zinc oxide is synthesized in nanosheet formwith 30 nmaverage thickness. By adding convection mass transfer (CMT), the length and width of nanosheets are strongly decreased and their thicknesses slowly increased to form nanoparticles. At higher convective mass transfer rates (more than 0.14 cm2 s-1), by increasing CMT rate, average particles sizes of the samples are decreased.