In this study, the dielectric properties of metal-oxide-metal capacitors based on Tantalum Titanium Oxide (TiTaO) thin films deposited by reactive magnetron sputtering on aluminum bottom electrode are investigated. The structure of the films was characterized by Atomic Force Microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The dielectric properties of TiTaO thin films were studied by complex impedance spectroscopy over a wide frequency range (10(-2) - to 10(5) Hz) and temperatures in -50 degrees C to 325 degrees C range. The contributions of different phases, phases' boundaries and conductivity effect were highlighted by Cole - Cole diagram (epsilon" versus epsilon'). Two relaxation processes have been identified in the electric modulus plot. A first relaxation process appears at low temperature with activation energy of 0.37 eV and it is related to the motion of Ti4+ (Skanavi's model). A second relaxation process at high temperature is related to Maxwell-Wagner-Sillars relaxation with activation energy of 0.41 eV. (C) 2016 Elsevier B.V. All rights reserved.