2-(5-Fluoro-3-methyl-sulfanyl-1-benzofuran-2-yl)acetic acid.

The title compound, C(11)H(9)FO(3)S, was prepared by alkaline hydrolysis of ethyl 2-(5-fluoro-3-methyl-sulfanyl-1-benzofuran-2-yl)acetate. In the crystal structure, the carboxyl groups are involved in inter-molecular O-H⋯O hydrogen bonds, which link the mol-ecules into centrosymmetric dimers. These dimers are further packed into stacks along the b axis by inter-molecular C-H⋯O and C-H⋯F inter-actions.