Three different morphologies of ZnO nanostructures were prepared by vapor transport on Au coated silicon substrates. Randomly oriented nanowires (NWs) mixed with few nanoflakes were obtained at furnace temperature of 750 °C and oxygen flow rate of 20 sccm. While thicker, longer and denser NWs were obtained at furnace temperature of 900 °C with the same oxygen flow rate of 20 sccm. Keeping the furnace temperature at 750 °C and lowering the oxygen flow rate to 5 sccm, changed the morphology of the NWs to unspecified features with few NWs in between. Both the growth temperature and the oxygen flow rate have proven to have great influence on stoichiometry. The control of the growth and stoichiometry of ZnO may have an impact in optoelectronic applications.