Dielectric properties of high-purity (4N degree) rutile TiO2 ceramics were investigated over a wide temperature (100-1073K) and frequency (20Hz-10MHz) ranges. X-ray photoemission spectroscopy measurement revealed the sample possesses mixed-valent states of Ti3+/Ti4+. Four thermally activated relaxations were observed. The lowest temperature relaxation (R1) features two Arrhenius segments with activation energy of 30 and 80meV for the low- and high-temperature segments, respectively. This relaxation was argued to be a polaron relaxation due to electrons hopping between Ti3+ and Ti4+ ions. The second relaxation (R2) appears around room temperature showing activation energy of 0.68eV is believed to be a Maxwell-Wagner relaxation. The high-temperature relaxations R3 and R4 with activation energy of 0.84 and 1.26eV were ascribed to the conduction process due to the hopping motions of singly and doubly charged oxygen vacancies, respectively.