Amidosulfites are chemical compounds containing the group =NS(O)O-. Substituents can attach two bonds to the nitrogen and one to the oxygen. These have the form RR'NS(O)OR" compounds can be a zwitterion with a positive charge on the nitrogen, and a negative charge on the oxygen, which then has no group attached. These can be called inner salts. This allows three groups to bond to the nitrogen: RR'R"N⁺S(O)O⁻.^[1]

The simplest amidosulfite is amidosulfurous acid H₂NS(O)OH. It has ammonium salt H₂NS(O)O⁻NH₄⁺. These are purportedly produced when sulfur dioxide mixes with ammonia in ratios 1:1 or 1:2.^[1]

Known compounds include N-(2-dimethylammonio-ethyl)amidosulfite, N-(2-diethylammonio-ethyl)amidosulfite, N-[2-(1-Piperidinium-1-yl)-ethyl]amidosulfite, N-[2-(4-Morpholinium-4-yl)-ethyl]amidosulfite, sodium N-ethylamidosulfite (C₂H₅NHS(O)ONa), Ethyl N-ethylamidosulfite (C₂H₅NHS(O)OC₂H₅), diethyl-phosphanyl N-methylamidosulfite, diphenyl-phosphanyl N-methylamidosulfite, N,N-dimethylamidosulfurous acid, N,N-diethylamidosulfurous acid, N,N-bis(2-hydroxyethyl)diethylamidosulfurous acid, sodium N,N-dimethylamidosulfite, sodium N,N-diethylamidosulfite, lithium N,N-diethylamidosulfite, lithium N-hexafluoroisopropylideneamidosulfite (with double bond to nitrogen), sodium 1-piperidinesulfinate Na(CH₂)₅NHS(O)O. ^[1]

Organometallic substituents can produce for example trimethylsilyl N,N-diethylamidosulfite, trimethyltin N,N-dimethylamidosulfite, or dimethylthallium N,N-dimethylamidosulfite.^[1]