Although some metal oxides eventually release O2 when heated, these conversions generally require high temperatures.  A few compounds release O2 at mild temperatures. Chemical oxygen generators consist of chemical compounds that release O when stimulated, usually by heat. They are used in submarines and commercial aircraft to provide emergency oxygen.  Oxygen is generated by the high-temperature decomposition of sodium chlorate:
:2 NaClO  →  2 NaCl  +  3 O
Potassium permanganate also releases oxygen upon heating, but the yield is modest.
:2 KMnO  →  MnO  +  KMnO  +  O