There has been tremendous interest in charge-transfer complex phenomena because of its wide applications in agricultural, industrial, biological activities, including anti-microbial, sedative, anticonvulsant and anti- inﬂammatory. Due to their cytotoxic, bactericide, and fungicide properties, CT complexes have found many applications in pharmaceutical industry. Some charge-transfer complexes have also been found to have high electrical conductivity. The objective of this work is to synthesize organic charge-transfer complexes in liquid and solid states and characterize them on the basis of spectroscopic techniques, including FT-IR, NMR, XRD, UV-Vis, Conductivity and Fluorescence spectroscopy. This book has been divided into four chapters. The first chapter is composed of an introduction on charge-transfer complexes, their types, theories and some characterization techniques. The Second, Third and Fourth chapters deal with the synthesis and spectral investigations electron-donor-acceptor-complexes in different polar solvents.