Ammonium Bisulfite, also known as ammonium hydrogen sulfate, is a white, crystalline solid when it is completely pure, with formula (NH4)HSO4. Pure ammonium bisulfite is a white crystalline solid. Commercially, aqueous liquid form is common. Ammonium bisulfite’s reductive and sulfonating properties provide versatile applications. It is used as an oxygen scavenger to eliminate the dissolved oxygen in waste water and in pipes.