Thiosemicarbazones are established as selective and sensitive analytical reagents for transition metals. This book describes literature survey and synthesis of some important thiosemicarbazones.As 2-hydroxy-4-n-butoxy-5-bromopropiophenone thiosemicarbazone (HBBrPT) is selective and strong chelating agent, it was developed as new reagent for spectrophotometric determination of micro quantities of cadmium. This extractive technique is found to be very simple, rapid and accurate for the determination of cadmium. The detailes of selection of pH, wavelength and solvent for the present system is reported. Validity of Beer''s law, molar extinction coefficient, Sandell''s sensitivity, Effect of foreign ion, etc. were investigated.Job''s method of continuous variation, the mole ratio and the slope ratio methods were studied. The stability constant and the free energy of the cadmium-HBBrPT complex were evaluated. The book is designed in the form of thesis work for Ph.D.degree so that reader can easily understand the work done by the authors. This book is very much useful for post graduate and research scholars to determine cadmium spectophotometrically.