A series of azo pyridone dyes derived by the coupling of 3-cyano-6-hydroxy-4-methyl 2 (IH) pyridone with diazotized para and meta substituted anilines, and the Cu(II) complex of the dyes, have been synthesized. The azo nyes and complexes have been characterized by elemental analysis, IR, H-1 NMR and UV-visible spectra. The acid dissociation constants of the dyes and formation constants of the complexes have been determined spectrophotometrically. Substituent effects on these parameters have been discussed. (C) 1997 Elsevier Science Ltd.