13-Nitro-benzo[a][1,4]benzo-thia-zino[3,2-c]phenoxazine.

In the title compound, C22H11N3O3S, dihedral angle between the phenyl rings on the periphery of the molecule is 8.05 (18)°. In the crystal, aromatic π-π stacking distance and short C-H⋯O contacts are observed. The maximum absorption occurs at 688 nm.