Azo dyes are the most important synthetic colourants which have been widely used in textile, paper manufacturing and printing. A novel disazo dye, 4 Bromophenylazo 2 naphtholazo 41 chlorobenzene was synthesized and characterized using UV Visible, FTIR spectrophotometric and elemental analytical tools. The result of the elemental analysis was found to be in conformity with the molecular formular of the dye. The UV Visible spectra indicated that the dye absorbed at visible region of 479.0 nm, characteristics of intensely coloured dyes. The FTIR spectral study showed absorption bands conforming to the various functional groups in the dye. The colour imparted by the dye on the tested fibres using Gray Scale for colour change, indicated excellent lightfastness, excellent heatfastness, and poor washfastness except nylon which showed fair washfastness. The toxicological testing indicated that the dye has no effect on the DNA of E.coli, and A.niger but at high concentration, it denatured human DNA. The dye does not have adverse effect on the growth of zea mays used for growth profile evaluation. Microbial toxicity of the synthesized dye on E.coli, A.niger and Bacillus cereus showed that all the strains are moderately resistant to the dye. Dye, 4 Bromoaniline, environment, fastness, toxicology, DNA. 29-36 Issue-4 Volume-10 Odilora, C. A | Orakwue, F. C. | Iloh, E. O | Okwuego, P. O.