In the title compound, C8H5ClN2O2 (common name: 5-chloroisatin 3-oxime), the molecular structure deviates slightly from the ideal planarity, with a maximum deviation of 0.0478 (8) Å for the non-H atoms. In the crystal, molecules are linked by N—H...O interactions, building centrosymmetric dimers with graph-set motif R22(8). Additionally, the molecules are connected by pairs of O—H...O interactions into chains along [100] with a C(6) motif. The hydrogen-bonded dimers and chains build a two-dimensional network parallel to (100). The packing also features π–π stacking interactions between benzene rings [centroid–centroid distance = 3.748 (2) Å].
