Addition of Ag+(aq) ions precipitates Ag2N2O2 from solution. The free acid is then prepared from silver hyponitrite and anhydrous HCl in ether:
Ag2N2O2 + 2 HCl → H2N2O2 + 2 AgCl
There are two possible structures of hyponitrous acid, trans and cis, and the solid Na2N2O2•5H2O is confirmed to be the trans form. Spectroscopic data also indicate a trans configuration of the free acid. The cis-form can be prepared as the sodium salt Na2N2O2 by heating Na2O with gaseous N2O.