Synthesis of some novel hetarylazoquinoline dyes was achieved by diazotisation of nine heterocyclic amines using nitrosyl sulphuric acid, coupling with 2,4-quinolinediol. These dyes were characterized by UV-vis. FT-IR and H-1 NMR spectroscopic techniques and elemental analysis. Visible absorption spectra of the dyes are discussed, both the effects of varying pH and solvent upon the absorption ability of azoquinolines. The colour of the dyes was discussed with respect to the nature of the heterocyclic ring and to the substituents therein. Temperature and concentration effects on the visible absorption maxima of the dyes are also reported. (c) 2005 Elsevier Ltd. All rights reserved.