Cresol red is a member of the class of 2,1-benzoxathioles that is 2,1-benzoxathiole 1,1-dioxide in which both of the hydrogens at position 3 have been substituted by 4-hydroxy-5-methylphenyl groups. It has a role as a dye, an acid-base indicator and a two-colour indicator. It is a polyphenol, a 2,1-benzoxathiole, a sultone and an arenesulfonate ester.
