In the crystal structure of the title salt hydrate, C9H8NO(+)·HSO4 (-)·H2O, the quinoline N-H atoms are hydrogen bonded to the bis-ulfate anions. The bis-ulfate anions and water mol-ecules are linked together by O-H⋯O hydrogen-bonding inter-actions. The cations and anions form separate layers alternating along the c axis, which are linked by N-H⋯O and O-H⋯O hydrogen bonds into a two-dimensional network parallel to (100). Further O-H⋯O contacts connect these layers, forming a three-dimensional network, in which two R 4 (4)(12) rings and C 2 (2)(13) infinite chains can be identified.