In the title compound, C(17)H(14)N(4)O(7)S, the dihedral angle between the two benzene rings is 9.04 (15)°. The centroid-centroid distance of 3.9825 (19) Å between nearly parallel benzene rings of adjacent mol-ecules suggests the existence of π-π stacking. Inter-molecular and intra-mol-ecular N-H⋯O hydrogen bonding is present in the structure. The eth-oxy group is disordered over two sets of sites with an occupancy ratio of 0.580 (15):0.420 (15). The crystal studied was an inversion twin.