In this work, we report on the electrochemical behavior of a test fuel cell manufactured entirely of perovskite like oxides, including a gallate supporting electrolyte (La0.85Sr0.15Ga0.85Mg0.15O3-δ, LSGM), a gallium doped cobaltite cathode (PrBaCo1.8Ga0.2O6–δ, PBCG), and a nickel doped iron-molybdate anode (Sr1.95Fe1.4Ni0.1Mo0.5O6–δ, SFNM). The distribution of relaxation times (DRT) method applied for deconvolution of the impedance spectra is indicative of the oxygen reduction rate at the PBCG cathode being faster than the oxidation of hydrogen at the SFNM anode surface. The cathode and anode processes are both so fast that the efficiency of the tested cell was limited solely by the electrolyte thickness. The cell with a 450 μm LSGM support demonstrated a power density of about 0.7 W cm−2 under wet hydrogen/air feed at 800 °C. The estimates show that the maximum power density at 800 °C can achieve about 2.5 W cm−2 for the assembly with a 20 μm thick electrolyte. © 2023 Elsevier Ltd