The structures of two isomeric compounds of 5-nitroquinoline with chloro-and nitro-substituted benzoic acid, namely, 2-chloro-4-nitrobenzoic acid-5-nitroquinoline (1/1), (I), and 5-chloro-2-nitrobenzoic acid-5-nitroquinoline (1/1), (II), both C7H4ClNO4·C9H6N2O2, have been determined at 190 K. In each compound, the acid and base molecules are held together by an O-H..N hydrogen bond. In the crystal of (I), the hydrogen-bonded acid-base units are linked by a C-H..O hydrogen bond, forming a tape structure along [1 0]. The tapes are stacked into a layer parallel to the ab plane via N-O..π interactions between the nitro group of the base molecule and the quinoline ring system. The layers are further linked by other C-H..O hydrogen bonds, forming a three-dimensional network. In the crystal of (II), the hydrogen-bonded acid-base units are linked into a wide ribbon structure running along [1 0] via C-H..O hydrogen bonds. The ribbons are further linked via another C-H..O hydrogen bond, forming a layer parallel to (110). Weak π-π interactions [centroid-centroid distances of 3.7080 (10) and 3.7543 (9) Å] are observed between the quinoline ring systems of adjacent layers. Hirshfeld surfaces for the 5-nitroquinoline molecules of the two compounds mapped over shape index and d norm were generated to visualize the weak intermolecular interactions.