This book contains nine series of organotin(IV) carboxylates with newely synthesized carboxylate ligands. The coordination mode of ligands, structural confirmation and geometry assignment of the complexes both in solid and solution states were made, using different analytical techniques such as FT-IR, multinuclear (1H, 13C and 119Sn) NMR and X-ray single crystal analysis. The interaction of the synthesized compounds with DNA was investigated by UV-visible spectroscopy and found an intercalative mode for interaction with DNA. Some of the synthesized compounds were also screened for their antibacterial, antifungal, antitumor, anticancer, urease inhibition and antileishmanial activities and found them active in each area of research. These compounds were tested for their catalytic activity in biodiesel synthesis. They possess high capability of catalyst in the conversion of corn oil into biodiesel. In present work, an environmentally benign process for the production of biodiesel from corn oil using heterogeneous catalyst was developed and got upto 99% conversion of oil into biodiesel. Thus the synthesized compounds may be used as one of the best choice catalyst in future.