5-(Pyridin-4-yl)isophthalic acid.

In the title compound, C(13)H(9)NO(4), the two carb-oxy-lic groups and the benzene ring are approximately co-planar with a maximum atomic deviation 0.175 (4) Å, while the pyridine ring is oriented at a dihedral angle of 31.07 (18)° with respect to the benzene ring. In the crystal, mol-ecules are linked by O-H⋯O, O-H⋯N and weak C-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular framework.