The story in this book is about a series of 1-(2- methoxyphenyl)-3-pivaloyl thiourea. substituted guanidine which were synthesized in good yield by condensation reaction of 1-(2-methoxyphenyl)-3- pivaloyl substituted thiourea with different aromatic amines by using HgCl2 as guanilating agent. These guanidines have a very high tendency to coordinate with Cu (II). All the spectroscopic results indicate that guanidines act as bidentate ligands through oxygen and nitrogen atoms. The products were characterized by using FT-IR, NMR (1H, 13C) and magnetic susceptibility techniques. The guanidines and their copper complexes were also subjected to various microorganisms in order to establish their bactericidal activity. In short this book is very much beneficial both for bigginers and for higher research scholars.