The double ordered perovskites NdBaCo2O5 and NdBaCo2O6 were prepared by soft chemistry. The samples were characterized from a structural and chemical point of view, concomitantly with their physical properties. Upon reduction, NdBaCo2O5 is formed with a tetragonal unit cell (a=b=3.94 angstrom, c=7.57 angstrom) and presents an antiferromagnetic behavior. Upon oxidation, a complete stoichiometric ordered phase NdBaCo2O6 with a tetragonal unit cell (a=b=3.88 angstrom, c=7.63 angstrom) could be obtained with a ferromagnetic and a metallic behavior. Finally it is shown that these phases are able to reversibly catch and release oxygen, suggesting a high anionic conductivity. (c) 2006 Elsevier B.V. All rights reserved.