Abstract: An anhydrous denture cleansing composition, having a free surface moisture content of less than 0.5% for dissolution in water to form a denture cleansing bath, consisting essentially of 10% to 40% by weight of a permonosulphate of the formula M.sup.1 HSO.sub.5 wherein M.sup.1 is an alkali metal cation; a tartar removal component selected from the group consisting of succinic acid, malic acid, tartaric acid, citric acid, a bisulphate of the formula M.sup.2 HSO.sub.4 wherein M.sup.2 is an alkali metal cation, and mixtures thereof; and an amount of a substantially chloride-free anhydrous alkali metal carbonate of formula M.sub.2.sup.3 CO.sub.3 wherein M.sup.3 is an alkali metal cation which amount is sufficient to develop an initial pH of .ltoreq.4.5 in the denture cleansing bath.