Here we present a systematic study on the morphological deviation of ZnO nanostructure (from sheets to micro-flowers) by varying pH of the solution via precipitation method. In this regard, zinc nitrate hexa-hydrate, NaOH and hydroxylamine hydrochloride (NH₂OH·HCl) were used. The solution of all three compounds was refluxed at a very low temperature (60°C) for short time (20 min). The solution pH was calibrated from 6 to 12 by the controlled addition of NaOH and HCl. We have observed from FESEM (field emission scanning electron microscopy) that the morphology of ZnO microballs composed with thin sheets markedly varies from sheet (at pH=6) to micro-flower composed with sheets of zinc oxide (pH=10–12). Further the morphology and crystallinity were also studied by the TEM (transmission electron microscopy) and HR-TEM (High resolution transmission electron microscopy) and it’s clearly consistent with the FESEM observations. The FTIR spectroscopic measurement also confirms the compositional analysis of ZnO and it comes in the range of 475 to 424 cm⁻¹ which is a standard peak of ZnO. In addition to this, the amount of H⁺ and OH⁻ ions are found a key to control the structure of studied material and discussed in the growth mechanism.