In this paper we report on crystal structure and oxygen storage properties of A-site cation ordered BaLnMn(2)O(5+delta) (Ln: Pr, Nd, Sm, Gd, Dy, Er and Y) perovskite-type oxides. The materials show practically complete and reversible change between fully reduced BaLnMn(2)O(5) and oxidized BaLnMn(2)O(6), which occurs at moderate temperatures (300-500 degrees C) during changes of the oxygen partial pressure (air, 5 vol.% H-2 in Ar). Based on the thermogravimetric measurements, reversible oxygen storage capacity, characteristic temperature of oxidation and reduction, as well as kinetics of these processes are given. Structural characterization was performed at room temperature for the reduced and oxidized materials by Rietveld analysis of the XRD data. These results are accompanied by in situ high temperature XRD measurements of the oxidation process, performed for BaNdMn2O5 in air. (C) 2015 Elsevier Ltd. All rights reserved.