Benzenesulfonic acid is an organic compound that consists of a benzene ring attached to a sulfonic acid group. Its chemical formula is C6H5SO3H. This compound is a colorless to yellowish liquid and is known for its strong acidity. It is commonly used in the production of detergents, dyes, and pharmaceuticals. The sulfonic acid group makes benzenesulfonic acid highly soluble in water, which enhances its utility in various chemical reactions. It can also act as a catalyst in organic synthesis. Additionally, benzenesulfonic acid derivatives are important in the development of sulfonamide antibiotics.