In order to evaluate applicability of Ce0.6 –хLa0.4PrхO2 – δ (x = 0–0.2) fluorites for protective interlayers and electrode components for intermediate-temperature solid oxide fuel cells (SOFCs), their thermal expansion, chemical interaction with solid electrolyte material, tolerance towards reduction and electrochemical behavior were studied. The incorporation of praseodymium into Ce0.6La0.4O2 – δ was found to increase unit cell parameters and thermal expansion coefficients, from (13.2 ± 0.3) × 10–6 to (18.5 ± 0.8) × 10–6 К–1 at intermediate temperatures. Increasing total concentration of rare-earth cations in the fluorite-like cerium dioxide structure also correlates with decreasing thermodynamic stability under both oxidizing and reducing conditions. As a result, high-temperature chemical interaction between the Pr-doped materials and lanthanum gallate-based solid electrolyte becomes more intensive with respect to Ce0.6La0.4O2 – δ, whilst reduction of Pr-containing solid solution may leads to segregation of a secondary phase with the C-type structure. The combination of these factors deteriorates compatibility of the interlayers with other SOFC components. Consequently, the overpotentials of PrBaFe1.2Ni0.8O6 – δ cathodes in the electrochemical cells with (La0.9Sr0.1)0.98Ga0.8Mg0.2O3 – δ solid electrolyte were –42 and –143 mV in O2 atmosphere at the current density –58 mA/cm2 and 1073 K when the interlayers of Ce0.6La0.4O2 – δ or Ce0.5La0.4Pr0.1O2 – δ were used, respectively.