(E)-2-Cyano-3-(2,3-dimeth-oxy-phen-yl)acrylic acid.

The asymmetric unit of the title compound, C(12)H(11)NO(4), contains two mol-ecules. In the crystal, neighbouring mol-ecules are linked together by O-H⋯O hydrogen bonds into dimers. The dimers are arranged into columns parallel to the a axis, meditated by π-π inter-actions [centroid-centroid distances = 3.856†(3) and 3.857†(3)†à ]. The crystal structure is further stabilized by weak inter-molecular C-H⋯O inter-actions. The crystal studied was a non-merohedral twin with a ratio of the twin components of 0.657†(11):0.343†(11).