A series of new heteroaryl azo dyes were synthesized by coupling of diazonium salts of various phenyl amine with newly synthesized imidazole - thiazole combined compounds. Namely N-((1H-benzo[d]imidazol-2-yl)methyl)-4- phenyl-4,5-dihydrothiazol-2-amine. It was prepared by simple condensation reaction of 2-chloromethyl benzamidiazol with 2-amino-4-phenylthiazole. It was characterized duly various aromatic amines were diazotized and the resultant diazonium salts were coupled with above compound. The so called result dyes N-((1Hbenzo[ d]imidazol-2-yl)methyl)-4-phenyl-5-(phenyldiazenyl)-4,5-dihydrothiazol-2-amine(Dye-A) obtained were characterized by elemental content, azo group determination and spectral studies. The dyeing performance of these dyes where assessed on polyester and nylon fabric. The dyes patterns were of various shades of red with good depth, brightness and leveling properties. The dyed fabric showed fairly good to very good light fastness and very good to excellent fastness to washing, perspiration and rubbing. The dye bath exhaustion and fixation on the polyester fabric was found to be very good.
