The book is given the idea about the coordination chemistry of thiosemicarbazides/thiosemicarbazones ligands with various metal complexes. Many functionally important biomolecules contain S-N donor site in suitable positions and the discovery of biological activities of various thiosemicarbazides/thiosemicarbazones and their metal complexes. Interest in the study of the chemical, biochemical and structural aspect of these compounds and their derivatives is growing. Though, the present effort summarized preparation of thiosemicarbazides/thiosemicarbazones ligands and their metal complexes. Characterization of metal complexes was studied on the basis of elemental analyses, mass spectra and FT-IR spectrum. Electronic spectral study along with magnetic data was examined to confirm the geometry of metal complexes. Also TGA were well discussed for decomposition temperature and degradation pattern. Further the biological evaluation was carried out for all the prepared compounds.