The reversible oxidation of barium oxide and the subsequent decomposition of barium peroxide are investigated by a volumetric measurement for the application to oxygen production, The reaction was run under isothermal and isobaric conditions at temperatures ranging between 600-950 degreesC and oxygen pressures up to 3 atm, and the equilibrium relationship between temperature, oxygen pressure and BaO/BaO2 composition was studied. The oxygen acceptor prepared by pelletizing a mixture of barium peroxide and magnesium oxide shows a long lifetime without disintegration and loss of reactivity, and high conversions are obtained in short reaction time of several minutes in both oxidation and reduction.