Dielectric behavior of PbZr 0.38 Ti 0.62 O 3 multilayer with alternating dense and porous PbZr 0.38 Ti 0.62 O 3 layers was investigated at 420K. Two distinct dielectric relaxation processes were observed in the frequency range from 102 Hz to 10 6 Hz. The relaxation at lower frequencies is attributed to the space charge polarization. The one at higher frequencies, with a thermal activation energy of 0.49 eV, might originate from the response of singly positive charged defect dipoles V ¨ 0 -Ti 3+ to ac electric fields. These dipoles are formed by the doubly ionized oxygen vacancies V 0 and trivalent titanium ions Ti 3+ as indicated by the results of Auger electron spectrum and electron paramagnetic resonance spectrum.