La2NiO4+δ, La1.4Ca0.6Ni0.6Fe0.4O4+δ (LCNF0604), La1.4Sr0.6Ni0.6Fe0.4O4+δ (LSNF0604), La1.4Sr0.6Ni0.5Fe0.5O4+δ (LSNF0605) and La1.5Sr0.5Ni0.6Fe0.4O4+δ (LSNF0504) were synthesized by the citrate-nitrate technique with the following four annealing steps at 950 °C in air (La2NiO4+δ, LCNF0604, LSNF0604) or in atmosphere with the reduced (10−5 atm) oxygen partial pressure (LSNF0605, LSNF0504). Phase purity of the samples is confirmed by the X-ray powder diffraction (XRPD). Electrochemical impedance spectroscopy studies of the symmetrical cells based on the proton-conducting La28−zW4+zO54+1.5z (z = 0.85, LWO85) electrolyte reveal that the polarization resistance (Rp) decreases in the row LCNF0604>La2NiO4+δ>LSNF0504>LSNF0604>LSNF0605 in the temperature interval of 600–800 °C in wet air. The process at low frequencies related to the surface exchange, provides the most significant contribution to the polarization resistance of the studied cells. Higher polarization resistance for the La2NiO4+δ/LWO85 cell can be associated with blocking of protons/protonic species. The minimal Rp value of 1 Ω cm2 at 800 °C in wet air is demonstrated by the LSNF0605/LWO85 symmetrical cell. The maximal power density for the anode-supported LSNF0605/LWO85/Ni-LWO85 single fuel cell is equal to 55 mW cm−2 at 750 °C. The performance of the fuel cell is limited by the formation of La2O3 at the LWO85/Ni-LWO85 interface due to chemical interaction between NiO and LWO85. To improve the performance of the studied fuel cell the development of new proton-conducting buffer layer stable to LWO85 is required.