Low-frequency dielectric dispersion phenomena in a LiTaO3-type single crystal have been analyzed by impedance spectroscopy in directions parallel and perpendicular to the polar c-axis (rhombohedral system). An empirical expression has been deduced for the complex permittivity ε*(ω), ε*(ω) = ε∞+ε5-ε∞1+(iω/ω1)m+σ0ε0ω[1+(iω/ω2)n],where the (ω1, m) and (ω2, n) couples characterize respectively the lattice and the charge carrier responses. This relation may be considered as a generalization of the Cole-Cole dielectric expression [J. Chem. Phys. 9, 341 (1941)]. Excellent agreement has been obtained in a wide frequency domain (1-106 Hz) between the measured and calculated permittivities in the 500-650°C temperature range (Tc = 600°C). The temperature dependence of various dielectrical parameters has been determined and discussed. The relaxations are correlated to Li atom motions.