Samples of Ni-doped CaCu₃Ti₄O₁₂ ceramics with the compositions of CaCu₃Ti_4-4хNi_4хO_12-δ and CaCu_3-3хNi_3хTi₄O₁₂ (x ≤ 0.06) were synthesized by the solid phase method. X-ray phase analysis revealed the trace amounts of copper oxide (II) admixture in the samples. Electrical properties of the samples of both compositions were studied in the temperature range of 25–400°С. The minimal dielectric loss tangent 0.07 and the maximal dielectric constant 6.0·10³ (at 1 MHz) were exhibited by the CaCu₃Ti_4-4хNi_4хO_12-δ (х = 0.03) ceramics at room temperature. The equivalent circuit was created based on the modeling of impedance spectra that well describe the electrical properties of the samples. It was proposed that the ionic charge transfer predominated in the studied samples at room temperature. This mechanism allows to explain the giant values of dielectric permeability and the high values of impedance phase at low frequencies. The electrical properties of Ni-doped CaCu₃Ti₄O₁₂ ceramics were analyzed and discussed.