ESR, XPS and NEXAFS spectra, as well as magnetic and electric properties of CaCu₃Ti₄O₁₂ synthesized by the solid-phase method within 6,12,24,48 and 60 h were studied. The analysis of magnetic susceptibility of CaCu₃Ti₄O₁₂ and magnesium-containing solid solutions of CaCu_3-3xMg_3xTi₄O₁₂ revealed antiferromagnetic exchange interactions between Cu paramagnetic atoms, while the effective magnetic moment of copper atoms corresponds to the electronic state of Cu(II). In CaCu₃Ti_4-4хMg_4хO_12-δ samples within the whole concentration range the impurity phase MgTiO₃ was observed. The magnetic properties of calcium copper titanate were found to be inconsistent depending on the synthesis duration. The extreme point of magnetic susceptibility was found among samples synthesized within 48 h. Modelling and interpretation of the XPS spectra of CaCu₃Ti₄O₁₂ were performed. Based on the NEXAFS and XPS spectroscopy data, copper and calcium atoms in ceramics display oxidation state +2, while titanium atoms – Ti(IV). ESR spectra of CaCu₃Ti₄O₁₂ samples show an exchange-narrowing signal from copper (II) atoms at g = 2.15. In the ESR spectra of CaCu_3-3xMg_3xTi₄O₁₂ the only intense exchange-narrowed line of Lorentzian form of Cu²⁺ ions is observed. The impedance spectroscopy study of electric properties of CaCu₃Ti₄O₁₂ found the media to feature temperature-dependent reach-through conductivity with activation energy of 0.79–0.71 eV. At 255–300°С, the dominant polarization process is in line with the Gerischer model. It indicates the formation of anionic-cationic associates accompanied by decreased low-frequency capacitance of the samples. With temperatures of over 300°С the samples start displaying ion-migrating polarization which contributes to higher capacitance and dielectric loss at low frequencies. As the temperature grows further to 400°С, the ion migration process gets to dominate within the whole frequency range under study. Based on the study, a conclusion was made on movable cations of copper participating in the polarization process at room temperature.