ZnO and ZnO: Mn nanocrystals synthesized via reverse micelle method. The structural properties nanocrystals were investigated by XRD and Transmission electron microscopy (TEM). The XRD results indicate that the synthesized nanocrystals had a pure wurtzite (hexagonal phase) structure. The various optical properties of these nanocrystals such as optical band gap energy, refractive index, dielectric constants and optical conductivity have been analyzed by using UV-Vis data. The refractive index decreases from 2.35 to 1.35 with the change of wavelength. The optical conductivity supports the accuracy of our energy band gap calculation. Room-temperature photoluminescence spectra of all the samples showed four main emission bands including a strong UV emission band, a weak blue band, a week blue-green band, and a weak green band which indicated their high structural and optical quality. Moreover the samples exposed to Gama rays sources of 137Cs and 60Co and their thermoluminescence properties were investigated. Their thermoluminescence response as a function of dose exhibited good linear ranges, which make them very promising detectors and dosimeters suitable for ionizing radiation.