Acesulfame potassium is a calorie-free artificial sweetener, also known as Acesulfame K or Ace K (K from Kalium, Latin for potassium), and marketed under the trade names Sunett and Sweet One. In the European Union it is also known under the E number (additive code) E950. It was discovered accidentally in 1967 by German chemist Karl Clauss at Hoechst AG (now Nutrinova). Alternatively, acesulfame K is often blended with other sweeteners (usually sucralose or aspartame). These blends are reputed to give a more sugar-like taste where each sweetener masks the other's aftertaste, and to exhibit a synergistic effect wherein the blend is sweeter than its components.
Unlike aspartame, acesulfame K is stable under heat, even under moderately acidic or basic conditions, allowing it to be used in baking, or in products that require a long shelf life. In carbonated drinks it is almost always used in conjunction with another sweetener, such as aspartame or sucralose.
As with sucralose, aspartame, stevia, saccharin, and other sweeteners that are sweeter than common sugars, there is concern over the safety of acesulfame potassium. Although studies of these sweeteners show varying and controversial degrees of healthfulness, the United States Food and Drug Administration (FDA) has approved these for use as general purpose sweetening agents, with the exception of stevia which is restricted to "dietary supplement" labeling. Japan, for instance, has approved stevia as a general purpose sweetener and it is found in many products. Other sweeteners that are banned in the USA are used in other countries, such as cyclamate, and vice-versa. Critics of the use of acesulfame potassium say the chemical has not been studied adequately and may be carcinogenic.