Effect of Mn doping on the structural, photoluminescence and photocatalytic photodegradation properties of Zn1−xMnxO have been studied. The Zn1−xMnxO powders and thin films were synthesized by the sol-gel, spin coating and high temperature annealing processes. The samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), photoluminescence and UV-visible (UV-Vis) spectroscopy. XRD analysis showed that Zn1−xMnxO can keep a single phase of wurtzite structure at low Mn doping. UV-Vis spectra of Mn-doped samples showed that Mn doping can enhance the decolorization efficiency of methyl orange at optimal Mn doping levels.