C2H5O4S is the chemical formula for a compound known as ethanesulfonic acid. This organic compound contains carbon, hydrogen, oxygen, and sulfur atoms. It is often used in various chemical applications, including as a reagent in organic synthesis and in the production of surfactants. Ethanesulfonic acid is a colorless, viscous liquid that is soluble in water. It is important in the field of chemistry for its role in creating other compounds and for its use in biochemical research. Its structure includes a sulfonic acid group, which contributes to its acidic properties and reactivity.