In this work, we studied the polarization resistance of the LaNiO3-δ/Ce0.8Sm0.2O2-δ symmetric cell by impedance spectroscopy in the temperature range of 600-800 °C in air. Analysis of the impedance spectra by constructing the Distribution Function of Relaxation Times showed that the polarization resistance of LaNiO3-δ can include up to 5 contributions. Among them, the processes of charge transfer through the electrolyte/electrode and electrode/gas phase interfaces and the "chemical" contribution, which includes oxygen diffusion and surface oxygen exchange in the electrode material. The resistance values for each contribution at different temperatures were obtained from fitting of the impedance spectra. The microstructure of LaNiO3-δ was studied by means of scanning electron microscope.