The dielectric absorption of some benzene derivatives and their binary mixtures has been studied at 3-cm. wave length microwave region in the range of temperature from 25 degrees C to 45 degrees C. The relaxation time. dipole moment, and the thermodynamic parameters for the dielectric relaxation as well as for viscous process have been measured. The results have been discussed on the basis of molecular size. molecular polarity. molecular environment, molecular interaction, effect of localization of charge density and contribution arising from the formation of H-bond structure.