Barium peroxide is an inorganic compound with the formula . This white solid (gray when impure) is one of the most common inorganic peroxides, and it was the first peroxide compound discovered. Being an oxidizer and giving a vivid green colour upon ignition (as do all barium compounds), it finds some use in fireworks; historically, it was also used as a precursor for hydrogen peroxide.
Barium peroxide consists of barium cations and peroxide anions . The solid is isomorphous to calcium carbide, .
Barium peroxide arises by the reversible reaction of with barium oxide. The peroxide forms around 500 °C and oxygen is released above 820 °C.
This reaction is the basis for the now-obsolete Brin process for separating oxygen from the atmosphere. Other oxides, e.g. and SrO, behave similarly.[1]
In another obsolete application, barium peroxide was once used to produce hydrogen peroxide via its reaction with sulfuric acid:
The insoluble barium sulfate is filtered from the mixture.