ZnO nanorods are grown on quartz substrates by metal organic chemical vapor deposition using diethylzinc (DEZn) and tert-butyl alcohol. Nanorods are grown basically by controlling the temperature and duration of growth at various steps. X-ray diffraction confirms the formation of ZnO naorods. FESEM images show the uniform distribution of nanorods on the substrate. The mechanism of formation of ZnO nanorods is proposed.