Two compounds, BaLa₂Fe₂O₇(s) and BaLaFeO₄(s) in the quaternary system Ba–La–Fe–O have been prepared by citrate-nitrate gel combustion route and characterized by X-ray diffraction analysis. Heat capacities of these two oxides were measured in the temperature range from 302 K to 832 K using a heat flux type differential scanning calorimeter. Two different types of solidstate electrochemical cells with CaF₂ as the solid electrolyte were employed to measure the e.m.f. as a function of temperature. The standard molar Gibbs energy of formation of the above oxides was calculated as a function of temperature from the e.m.f. data. The standard molar enthalpy of formation at 298.15 K, Δ_fH°
_m (298.15 K) and the standard entropy S°
_m (298.15 K), of these two oxides were calculated by second law method. The values of Δ_fH°
_m (298.15 K) and   S°
_m (298.15 K) obtained for BaLa₂-Fe₂O₇(s) are: -3446.4 kJ · mol^-1 and 246.6 J · K^-1 · mol^-1 whereas those for BaLaFeO₄(s) are: -2080.4 kJ · mol^-1 and 95.0 J · K^-1 · mol^-1, respectively.