Abstract: Improved oxygen generating agents and oxygen generating catalysts are disclosed. The oxygen generating agent comprises sodium carbonate peroxyhydrate, 2Na.sub.2 CO.sub.3.3H.sub.2 O.sub.2, as an oxygen generating source and calcium carboxymethyl cellulose (Ca-CMC) as a bonding agent. The oxygen generating catalyst comprises hydrogen peroxidase as an essential ingredient, and salt cake and polyvinyl alcohol (PVA) as accessory ingredients. The hydrogen peroxidase, the salt cake and the PVA are kneaded with each other and, thereafter, granulated or tabletted so as to form the catalyst. The oxygen generating agent of this invention provides a stable oxygen supply for a long time. This agent is also remarkably improved in its preservation. The oxygen generating catalyst permits free control of the lasting time of oxygen generating reaction. This catalyst can be preserved free from deterioration of its performance for a long time.