The production of stable dispersions of carbon nanotubes (CNTs), synthesized by CVD, in different liquids, is one of the methods of preparation of CNTs for introduction into polymeric matrix. The aim of this work is to produce composites of polyethylene (PE) – CNT, and the study of their structural characteristics, mechanical, thermodynamic, and kinetic properties as dependent on the concentration of multi-walled CNTs and the preliminary dispersion by several methods. Multi-walled CNTs were synthesized by catalytic pyrolysis (CCVD) using iron-containing catalyst in admixture with pyrogenic silica (grade A 300), which was prepared by coprecipitation of hydroxides of aluminum, magnesium and divalent iron. CNTs with a diameter of 10–20 nm were grown in a reactor with a volume of 24 dm 3 with a smooth mixing of the catalyst layers due to rotation of the reactor. Deagglomeration of CNTs was carried out by processing in an ultrasonic dispergator or in a device that combines the cavitation mixing and shear deformation in aqueous solutions of different composition. Composite samples of the of PE–CNT with different concentration of the filler obtained by hot pressing at the temperature of 140 °C and the pressure of 5 MPa of polyethylene powders. Their surface was pre-deposited CNTs from stable aqueous dispersions. The structural characteristics of the CNTs and the composite of PE–CNTs is determined by the methods of transmission electron microscopy (JEM-100CXII), X-ray diffraction (DRON-3M, λСо = 0.179 nm). Structural and phase transitions and the processes of destruction of polymer composites in air are investigated by methods of DTA and DTG on a derivatograph Q 1500 D (Hungary). Electric conductivity at low frequencies (0.1, 1 and 10 kHz) was measured by double contact method with an immittancemeter E7-14. The frequency dependence of complex electric conductivity of the composites was evaluated from calculations of the impedance spectra in the frequency range 10 -2 –10 6 Hz obtained by an impedance spectrometer Solartron SI 1260. The carbon nanotubes (CNTS) introduction in a matrix of polyethylene in small amounts (up to 5 wt. %) leads to a nonmonotonic change of the degree of crystallinity of the matrix. Their electrophysical and thermodynamic properties were studied. The percolation threshold in systems PE–CNTs from certain experimental data on the electrical conductivity is in the range 0.0015–0.0020 in volume. The content CNT to 2 % increases the temperature of the thermal oxidative degradation of the polymer by almost 60 °C. Influence of CNTs on the structure and properties of the composite is the more significant, the greater the degree of CNTs deagglomeration.