This book gives an idea about Coordination chemistry and its applications. The book represents applications of various coordination compounds. It highlights one heterochelate ligand containing "N" and "O" as donor atoms, named Kynurenic acid (KYNA), which is a very important neurological drug with various biological applications. The book also includes the details about 3d metal ions complexes with their important kinetic study and catalytic study. Complexes of selected 3d and d10 metal ions with ligand (kynurenic acid), were very much effective to proliferate the rates of selected reduction, oxidation and reductive coupling reactions to a considerably high extent. It was observed that all the complexes proved to be very good catalysts.