This book describes the synthesis and characterization using proton-NMR, IR, CHNS analyzer, single crystal X-ray diffractometer and quantum chemical studies of novel derivatives of 5-aminotetrazole. The reactions involving acid chlorides were performed in inert atmosphere. The reactions with sulfonyl chlorides gave products with cleaved tetrazole ring structure. In 1H NMR spectrums, aromatic protons were observed at d 7.4-7.9 ppm in all derivatives. The density functional theory has been used to investigate the geometric and electronic properties of all the compounds. The B3LYP/6-311G** level of theory was found better than the B3LYP/6-31G** level of theory to reproduce the experimental data. The HOMOs and LUMOs of all the compounds under study were also calculated.