In the present study Zinc Oxide (ZnO) and Manganese (Mn) doped ZnO (ZnO: Mn) nanoparticles are synthesized by using hydrothermal method. Structural properties of synthesized sample was studied by using X-ray diffraction (XRD) and exact fitting of peaks was done by using Rietveld Refinement with Crystallographic Open Database(COD).It reveals that ZnO and Mn doped ZnO nanostructures follows hexagonal wurtzite structure with P-63mn space group. Williamson-Hall (W-H) plot method was used to determine the value of lattice strain and crystallite size on the samples. From W-H plot it was found that Mn doped ZnO nanostructures follows a positive strain value but ZnO follows a negative strain value. A comparison relating to the difference in strain values due to the presence of dopant in lattice is illustrated. Optical properties and bandgap values of ZnO and ZnO:Mn was verified by using UV-Visible spectroscopy and Photoluminescence (PL) spectroscopy respectively. Tauc plot was used to confirm the variation in bandgap values of ZnO and ZnO:Mn and there occurs a redshift in the bandgap values due to doping. The oxidation states of the elements are determined by using X-ray photoelectron Spectroscopy (XPS). Morphological properties and elemental composition were studied by using Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive Spectroscopy (EDS) respectively. Adsorption capacity and photocatalytic degradation of malachite green dye using ZnO and ZnO: Mn nanostructures as photocatalyst is verified. Mn doped ZnO nanostructures possess higher photocatalytic activity than pure ZnO nanostructures. Influence of Mn doping on the adsorption and photocatalytic behavior is studied.