Pyronin Y (PY) is an organic dye belonging to xanthene derivatives which was used extensively in the past for staining RNA and other organocells. Nowadays, it is used in electronic and optoelectronic devices as an organic semiconductor. X-ray diffraction (XRD) showed that PY is a polycrystalline material and both the lattice structure and the lattice constants were calculated for the first time by using crysfire and checkcell software. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) have been studied for pyronin Y. Diffused reflectance (DR) of pyronin Y in the wavelength 200-2300 nm was measured and analyzed to calculate the optical parameters and the absorption region of the pyronin Y. The optical band gap was calculated...