The mol-ecule of the title compound, C(10)H(11)N(3)O(3), adopts an all-trans conformation and is approxomately planar, the largest deviation from the least-squares plane through all non-H atoms being 0.261 (1) Å. An intra-molecular O-H⋯N hydrogen bond occurs. In the crystal, the mol-ecules are packed into layers lying parallel to the ab plane by π-stacking inter-actions between the benzene ring of one molecule and the C-N bond of the oxime group of another molecule; the shortest inter-molecular C⋯C separation within the layer is 3.412 (1) Å. The layers are connected by O-H⋯O and N-H⋯O hydrogen bonds.