Abstract: The dyestuff industry has come under pressure in recent times to minimize the damage to the environment caused by the production process and its effluents. In the present investigation we have synthesized and characterized some disazo dyes from a more environmentally friendly heterocyclic compound, 5-Amino-2-mercapto-1,3,4-thiadiazole as the nucleus of the dyes. In preparation of the dyes, the aforementioned intermediate was diazotized and coupled with 2-chloroaniline to give another intermediate diazo compound, 2-mercapto-1,3,4-thiadiazoleazo-4-amino-3-chlorobenzene. This was subsequently diazotized and coupled with other couplers to afford the disazo dyes. The results of fastness properties of the dyes on acrylic fabric and nylon fabric gave excellent sublimation ratings, excellent washing treatment, perspiration ratings and good light fastness ratings. Thus, all the dyes showed strong affinity for the polymers used for the study as exemplified by the wet fastness and the bright shades on the two fibres. The dyes were characterized using IR, UV-VIS, 1HNMR and 13C NMR analyses.