Charge transfer complexes between 2,3-dichloro-5,6-dicyano-p-benzoquinone and various methyl and phenyl substituted benzenes have been studied. The spectral characteristics and equilibrium constants of o-, m-, and p-xylenes and those of o-, m-, and p- terphenyls are reported. The results have been interpreted in terms of Mulliken’s charge transfer theory. From the spectral data, the electron affinity of 2,3-dichloro-5,6-dicyano-p-benzoquinone has been estimated to be 1.974 eV. The energy of the first CT band has been found to be related to the ionization potential of the donors by the expression hϑCT=0.7ID−3.86.