In the title solvate, C19H13N5O center dot 0.5C(4)H(8)O(2), the main molecule is almost planar (r.m.s. deviation for the non-H atoms = 0.066 angstrom). The hydroxylamine group is disordered over two orientations in a 0.761 (4): 0.239 (4) ratio. The complete dioxane solvent molecule is generated by a crystallographic inversion centre. In the crystal, both disorder components of the hydroxylamine group form O-H center dot center dot center dot N hydrogen bonds to the same N-atom acceptor, thereby generating  chains. The chains encompass  channels occupied by the solvent molecules. Aromatic pi-pi stacking is also observed [shortest centroid-centroid separation = 3.3394 (19) angstrom].