In the title compound, C9H8N2O2S, the sulfamoyl -NH2 group is involved in inter-molecular hydrogen bonding with the sulfonamide O and quinoline N atoms. In the crystal, mol-ecules are linked into dimers via pairs of N-H⋯N hydrogen bonds, forming an R 2 (2)(10) motif. The dimers are further assembled into chains parallel to the b axis through N-H⋯O hydrogen bonds, generating a C(4) motif. The crystal packing is additionally stabilized by inter-molecular C-H⋯O inter-actions. The crystal studied was a non-merohedral twin with a domain ratio of 0.938 (2):0.062 (2). Density functional theory (DFT) calculations, at the B3LYP/6-31 G(d,p) level of theory, were used to optimize the mol-ecular structure and to determine inter-action energies for the title compound. The resulting inter-action energy is ∼4.4 kcal mol(-1) per bridge for the C(4) chain and ∼5.9 kcal mol(-1) per bridge for the R 2 (2)(10) motif.