6-Hy-droxy-1,2-dihydro-4H-pyrrolo-[3,2,1-ij]quinolin-4-one.

The mol-ecule of the title compound, C11H9NO2, is essentially planar [r.m.s. deviation of the non-H atoms = 0.056 (1) Å]. In the crystal, strong O-H⋯O hydrogen bonds form zigzag chains along the b axis. The mol-ecules form stacks along the a axis due to π-π inter-actions, the shortest distance between the centroids of the benzene and pyridinone rings being 3.6146 (7) Å.