Peroxynitric acid

Peroxynitric acid or peroxonitric acid is a chemical compound with the formula. It is an oxyacid of nitrogen, after peroxynitrous acid.

Preparation
Peroxynitrate, the conjugate base of peroxynitric acid, is formed rapidly during decomposition of peroxynitrite in neutral conditions.

Atmospheric chemistry
Peroxynitric acid is formed in the atmosphere, although it is unstable, it is important as a reservoir for NO2 through the reversible radical reaction: