The book includes the synthesis, characterization and X-ray analysis of organotin(IV) carboxylates and organotin(IV) thiocarboxylates. Various di- and triorganotin(IV) compounds have been synthesized with a stoichiometric amount of synthesized carboxylic acid and thiocarboxylic acid. The structural assignments were made on the basis of spectral techniques such as FT-IR, 1H, 13C, 119Sn NMR and mass spectrometry, which ascertain the tetrahedral environment around the tin atom in solution while penta or hexa coordination is found in the solid state. Biological activity tests of the synthesized carboxylates and thiocarboxylates were made against various medically important bacteria and fungi. Most of the compounds were found to show activity with a few exceptions. These compounds were also evaluated for their cytotoxicity using the brine-shrimp lethality bioassay method. Only few of the compounds were found to be nontoxic