Abstract
The crystal structure of the title compound, 4-hydr-oxy-2-pyridone, C(5)H(5)NO(2), which has been the subject of several determinations using X-rays and neutron diffraction, was first reported by Low & Wilson [Acta Cryst. (1983). C39, 1688-1690]. It has been redetermined, providing a significant increase in the precision of the derived geometric parameters. The asymmetric unit comprises a planar 4-enol tautomer having some degree of delocalization of π-electron density through the mol-ecule. In the crystal structure, the mol-ecules are connected into chains by two strong O-H⋯O and N-H⋯O hydrogen bonds between the OH and NH groups and the carbonyl O atom.