Infrared and Raman spectra of solid LiNO2•H2O, LiNO2, NaNO2, KNO2, and CsNO2 are presented and discussed. Pronounced changes in the spectra of LiNO2•H2O during dehydration to anhydrous LiNO2 are interpreted as evidence for an ordered distribution of NO2− ions over two non-equivalent sites (akin to linkage isomerism) in anhydrous LiNO2. The frequencies of the internal modes of the nitrite ion shift to lower values with increasing cation size. Vibrational bands due to nitrate ion present as an impurity are assigned.