The molecule of the title compound, C11H9NO3, a pharmacologically important quinoline derivative, adopts an overall planar shape. The structure is stabilized by an intra-molecular O - H⋯O=C hydrogen bond, forming an S(6) hydrogen-bonded ring pattern. The O - H⋯O inter-action results in delocalization of the electron density within the dihydro-pyridine ring, as observed for resonance-assisted hydrogen bonds, leading to lengthening of the carbonyl O=C and pyridyl C=C bonds, and shortening of the C - OH bond in this hydrogen-bonded S(6) ring structure. The cooperative inter-molecular N - H⋯O hydrogen bonds cluster mol-ecules into closed dimers, characterized by an R 2 2(8) ring pattern. Aromatic-aromatic stacking inter-actions are also observed in the packing, with an inter-planar distance of 3.352 Å and a slippage of 1.855 Å © International Union of Crystallography 2007.