PURPOSE: To adsorb oxygen alone selectively without reducing the adsorption capacity for oxygen by inhibiting the adsorption of nitrogen substantially by using a selective adsorbent for oxygen prepd. by depositing fine silica on Na A type zeolite as carrier.

CONSTITUTION: A selective adsorbent for oxygen is constituted of Na A type zeolite having fine silica deposited thereon. Preferred amt. of deposited silica is ≥2wt% and ≤20wt% basing on the amt. of zeolite. The silica to be deposited should be fine and hydrated. Namely, fine silica is contained in the slurry of Na A type zeolite. Fine silica is deposited on the particles of the zeolite, and washed with water after separating solid from liquid by the conventional method, and then dried. The dried product is heated at ≥ca. 450°C to prepare the product. Obtd. product inhibits adsorption of nitrogen substantially, and absorbs oxygen along without causing deterioration of adsorption capacity.