4-Hy-droxy-6-methyl-3-[3-(thio-phen-2-yl)acrylo-yl]-2H-pyran-2-one.

The title compound, C13H10O4S, crystallizes with two mol-ecules in the asymmetric unit in which the rings make dihedral angles of 3.9 (1) and 6.0 (1)°; this planarity is due in part to the presence of an intra-molecular O-H⋯O hydrogen bond, which generates an S(6) ring in each mol-ecule.