First principle calculations were performed to investigate the electronic band structure, density of states, charge density and optical properties of 5-azido-1H-tetrazole. The calculated band structure shows that the compound is a semiconductor having indirect 0 A band gap. The total valance charge density in 9 0 4 plane shows the covalent nature of the bonds in 5-azido-1H-tetrazole molecule. The compound 5-azido-1H-tetrazole contains four homodimers. In each homodimer the molecules held together by hydrogen bond of about 1.74 Å. The calculated bond length, angles and torsion angles of 5-azido-1H-tetrazole show close agreement with experimental results. The average value of real and imaginary part of dielectric function was calculated. The three principal tensor components of) (2 ,) (1 ,) ( n ,) ( I and) ( R were investigated. The calculated band gap's values and optical properties show that the investigated compound is suitable for optoelectronic devices in far-ultraviolet (UV-C) region.