The dielectric permittivity of polycrystalline Li2SO4 was measured from 5 Hz to 13 MHz and over the temperature range 235-460 °C. The corrected imaginary part of permittivity, ϵ″, and its real part ϵ′ vs. frequency clearly show a new dielectric relaxation around fmax = 2 × 104 Hz at T = 256 °C, which shifts to higher frequencies (∼1 MHz) as the temperatures increases. The relaxation frequency (calculated from the peak position of ϵ″) vs. reciprocal T shows an activated relaxation process with activation energy Ea= 0.9 eV, which is very close to that derived from the dc conductivity, Eσ (0.87 eV). We suggest that this dielectric relaxation could be due to the Li+ jump and SO4– reorientation that cause distortion and change of the local lattice polarizability inducing dipoles like LiSO4–. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)