The complex permittivity at microwave frequencies of benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene was measured at 25 degrees C. Given the extremely low conductivity of these solvents, the measurements were made using microwave re-entrant resonant cavities for nine frequencies between 170 MHz and 8.5 GHz. As a function of frequency, the dielectric constant follows a linear behavior with small decay, and the imaginary part follows a linearly increasing behavior. In addition, a relation between the permittivity measurements and their respective polarizabilities is proposed and tested.