The chemical group "-SO3H" is known as a sulfonic acid group. It consists of a sulfur atom bonded to three oxygen atoms and a hydrogen atom. This functional group is commonly found in various organic compounds, contributing to their acidic properties and enhancing their solubility in water. Sulfonic acids, which contain the -SO3H group, are important in many applications, including detergents, dyes, and pharmaceuticals. One well-known example is benzenesulfonic acid, which is used in the production of surfactants and as a catalyst in chemical reactions.