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Brownmillerite-structured Ca 2 AlMnO 5 is inexpensive and capable of rapid oxygen storage and release. This study focused on improving the oxygen storage/release rate of Ca 2 AlMnO 5 , which is essential for its application in practical oxygen production systems. Two approaches were investigated for improving the oxygen-trapping ability of Ca 2 AlMnO 5 : heat treatment for 2 h and 24 h after solution combustion synthesis (SCS) and the addition of Pt nanoparticles as a catalyst. Noticeably, crystalline Ca 2 AlMnO 5 was formed after heat treatment at 1250 °C for at least 2 h. For the 2-h heat treatment, the average particle size of Ca 2 AlMnO 5 was 11.4 μm, while that for the 24-h treatment was 18.9 μm. This reduction in the particle size increases the oxygen storage/release rate because of the relatively short diffusion distance within the particles. The oxygen storage rate increased with the addition of Pt nanoparticles because the nanoparticles were distributed across the surface and acted as catalyst. This catalyst accelerated the oxygen-evolution reaction by activating the surface reactions between oxygen ions and the Ca 2 AlMnO 5 particles. The short 2-h heat treatment prevented the Pt nanoparticles from aggregating. When the Pt nanoparticle addition was implemented in combination with the 2-h heat treatment, the storage and release rates were drastically improved, i.e., by 2.5 and 6.1 times, respectively, compared with the sample after 24-h heat treatment without Pt nanoparticles. The oxygen storage/release rate remained constant even after repeated use at 550 °C, for over 25 cycles. Furthermore, Ca 2 AlMnO 5 suffered no surface damage, and none of the Pt nanoparticles re-agglomerated after this test, further indicating the durability of the treated material. • Solution combustion synthesis of Ca 2 AlMnO 5 as oxygen storage material was studied. • Effects of heating time and Pt nanoparticles as catalysts were investigated. • Short heat treatment and Pt addition increased the storage/release rate. • The combination of Pt addition and 2 h heat treatment was a good condition. • The Pt/2 h condition achieved 2.5- and 6.1-times higher storage and release rates. [ABSTRACT FROM AUTHOR]