The formation of molecular complexes between electron donors and acceptors is an important phenomenon and has been well established. Charge transfer complexes of eight donors (antiviral drugs) with π-acceptors such as substituted quinines have been studied to understand the reactivity of drugs directly by calculating CT energies and ionization potentials of the drug molecules. CT complexes of intense colour are developed by interacting donor and acceptors in 1:1 ratio in dichloromethane. CT transition energies and ionization potential were calculated from the absorption maxima (nm) of the CT complexes. Abacavir, oseltamivir, ritonavir and tenofovir have formed strong complexes with the π- acceptors i.e. the interaction between them is high when compared with other donors.