A batch process for co-producing anhydrous hydrogen bromide and a purified bisulfate salt comprising: (a) charging a batch reactor with a bromide salt slurry, wherein the slurry is more than 50% by weight bromide salt; (b) reacting the slurry with sulfuric acid in a batch reaction wherein bromide salt is consumed to produce crude aqueous hydrogen bromide and crude bisulfate salt, the crude bisulfate salt containing bromine; (c) prior to or concurrently with step (b) adding hydrogen bromide to the reactor; (d) purifying the crude hydrogen bromide to produce anhydrous hydrogen bromide; and (e) removing bromine from the crude bisulfate salt to form a purified bisulfate salt.