Adducts (1 : 1) of copper(I) chloride, bromide and thiocyanate with quinoline have been synthesized and have been the subject of single-crystal X-ray structure determinations at 295 K. Crystals of the chloride are orthorhombic, P 212121, a 15.358(7), b 14.309(6), c 3.801(2)?, Z 4; R was 0.055 for 541 'observed' reflections. Crystals of the bromide are monoclinic, C2/c, a 19.417(5), b 14.048(4), c 15.753(6) ?, ߠ125.31(2)ଠZ 4 tetramers; R was 0.049 for 1138 'observed' reflections. Crystals of the thiocyanate are monoclinic, P 21/c, a 5.682(1), b 10.412(2), c 16.838(5)?, ߠ97.48(2)ଠZ 4 f.u .; R was 0.045 for 914 'observed' reflections. The chloride takes the form of the common 'stair' polymer, unexpectedly, while the thiocyanate is an expanded version of the same. The bromide provides a second example of a novel tetrameric 'basket' structure exemplified previously by the iodide analogue.