A new medium-temperature (200-400℃) adsorbent material for oxygen removal and air separation, YBaCo_4O_(7+β), was prepared by the solid-state reaction method. This new adsorbent could adsorb a large quantity of oxygen in the temperature range of 200-370 ℃. Ad-sorbed oxygen could be released by raising temperature over 400 ℃ or by switching the atmosphere from oxygen to nitrogen. This oxygen adsorption and desorption process had good reproducibility. Taking advantage of this unique oxygen intake/release behavior, a nitrogen puri-fication process was investigated. The results showed that YBaCo_4O_(7+δ) material was a promising candidate for the oxygen sorption process and could be used to produce high-purity nitrogen or to remove trace oxygen from other gases.