Flower-like zinc oxide (ZnO) micro-/nano-structures are synthesized as thin films on glass substrates by the spray pyrolysis technique at a substrate temperature of 350 ± 5°C. The films are characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM) and x-ray energy dispersion spectroscopy (EDS). Absorbance spectra (UV-Vis) and ImageJ software is used for size analysis. The XRD diffractogram revealed that the films have a hexagonal (wurtzite) phase with preferential orientation along the (002) line. SEM images showed that the films have a micro/nano flower-like structure. EDS spectra revealed that the films contain chlorine in addition to zinc and oxygen. Absorbance measurements were used to estimate the band gap energies, which were found to be larger than the bulk... value. Such morphologies and band gap values are advantageous when using ZnO as fore contact and/or window material in thin-film solar cells and photoanodes in dye-sensitized solar cells, optoelectronic devices and gas sensors.