In the title compounds, N -(5-acetyl-2-methylphenyl)quinoline-2-carboxamide [C 19 H 16 N 2 O 2 , (I)], N -(5-acetyl-2-bromophenyl)quinoline-2-carboxamide [C 18 H 13 BrN 2 O 2 , (II)] and N -(5-acetyl-2-ethynylphenyl)quinoline-2-carboxamide [C 20 H 14 N 2 O 2 , (III)], the quinoline ring system is essentially planar and forms a dihedral angles of 3.68 (5) (I), 5.59 (7) (II) and 1.87 (6)° (III) with the acetyl-substituted ring. The molecular structures of (I) and (III) each feature an intramolecular N—H...N hydrogen bond, forming an S (5) ring, while in (II) an intramolecular bifurcated N—H...(N,Br) hydrogen bond forms two S (5) rings. In the crystals, weak C—H...O hydrogen bonds link molecules of (I) into C (7) chains long [010], molecules of (II) into chains of R 2 2 (8) rings along [110] and molecules of (III) into C (8) chains along [010]. In (I), there are no significant π–π stacking interactions under 4 Å, but in both (II) and (III), π–π interactions link the weak hydrogen-bonded chains into layers parallel to (001) [centroid–centroid disttances of 3.748 (1) Å in (II) and 3.577 (1), 3.784 (1) and 3.780 (1) Å in (III)].