Monosodium citrate, more correctly, sodium dihydrogen citrate (Latin: natrium citricum acidulatum), is an acid salt of citric acid. Disodium citrate and trisodium citrate are also known. It can be prepared by partial neutralisation of citric acid with an aqueous solution of sodium bicarbonate or carbonate. It has a slightly acidic taste.

It is highly soluble in water and practically insoluble in ethanol. Monosodium citrate is used as an anticoagulant in blood samples. It is used as an alkalinizing agent to prevent kidney stone disease. The crystals form as nearly perfect cubes.