This book discusses spectral (IR, electronic and EPR) and magnetic properties, as well as crystal structures of CuII complexes with pyridinecarboxylic acids which contain carboxyl group in 3- or 4-position of the pyridine ring. For the preparation of pyridinecarboxylato copper (II) complex compounds with aliphatic, as well as aromatic chelating ligands and N-heterocyclic ligands, only conventional methods have been used. Spectral, magnetic and structural characterisation of the prepared complexes is important to understand the relations between their structure and biological activity. This book presents data which determines that both carboxylic acids and their CuII complexes are some of the possible ways of finding suitable preparations with biological effects.