A facile, mechanical milling method resulting in a significant improvement of the oxygen release kinetics from cation-ordered BaLnMn(2)O(5+delta)-type (Ln: selected lanthanides) materials is shown for Pr- and Sm-containing compounds. Synthesized by a soft chemistry method, BaPrMn2O5 and BaSmMn2O5 oxides were milled in an appropriately selected conditions, which allowed to obtain samples with largely decreased crystallite size, increased specific surface area, and likely, having a partial Ba-Ln disorder. Such materials were characterized in terms of their oxygen storage-related properties and were found to exhibit enhanced oxygen release kinetics, with a reduction rate parameter being increased several times. The milling process did not influence the mechanism of the oxygen release significantly. A decrease of a characteristic temperature of reduction was also noticed, however, while the oxygen storage capacity of BaSmMn2O5+delta was found to increase after milling, it decreased for BaPrMn2O5+delta. It seems that the enhanced reduction rates can be related to a diminished tendency of a formation of the oxygen vacancy-ordered BaLnMn(2)O(5.5). The reported studies are supplemented by scanning electron microscopy and X-ray photoelectron spectroscopy measurements. (C) 2016 Elsevier B.V. All rights reserved.