In the structure of the title compound, C(12)H(11)N(3)O(3)·H(2)O, the dihedral angle formed by the benzene and isoxazole rings is 2.03 (8)°. The mol-ecular conformation is stabilized by an intra-molecular O-H⋯N hydrogen bond. In the crystal structure, mol-ecules are linked into a three-dimesional network by inter-molecular N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds, and by π-π stacking inter-actions involving adjacent benzene and isoxazole rings [centroid-centroid separation = 3.663 (2) Å].