Acesulfame potassium (ace-SUHL-faym), also known as acesulfame K (K is the symbol for potassium) or Ace K, is a calorie-free sugar substitute (artificial sweetener), and marketed under the trade names Sunett and Sweet One. In the European Union, it is known under the E number (additive code) E950. It was discovered accidentally in 1967 by German chemist Karl Clauss at Hoechst AG (now Nutrinova). In chemical structure, acesulfame potassium is the potassium salt of 6-methyl-1,2,3-oxathiazine-4(3H)-one 2,2-dioxide. It is a white crystalline powder with molecular formula C₄H₄KNO₄S and a molecular weight of 201.24 g/mol.