亚硫酸氢钠（化学式：NaHSO₃），白色结晶性粉末，有二氧化硫的气味，可溶于水，也微溶于醇。其在空气中易被氧化为硫酸盐。

亚硫酸氢钠与活泼醛、酮发生加成反应，生成亚硫酸氢钠加合物。该反应可用来避免羰基和HCN加成时剧毒HCN的使用，方法为：先使羰基化合物与亚硫酸氢钠加成，再加入等物质的量的NaCN。

可由焦亚硫酸钠加水制备，化学式为：
Na₂S₂O_5(s)+H₂O_(l)→2NaHSO_3(aq)

Sodium bisulfite (sodium hydrogen sulfite) is a chemical compound with the chemical formula NaHSO₃. Sodium bisulfite is a food additive with E number E222. This salt of bisulfite can be prepared by bubbling sulfur dioxide in a solution of sodium carbonate in water. Sodium bisulfite in contact with chlorine bleach (aqueous solution of sodium hypochlorite) will generate heat and form sodium bisulfate and sodium chloride.