The aim of this work is to synthesize a new type of reactive disperse dye having an acetoxyethylsulfone group which is expected to have the favorable properties of both a disperse dye and a reactive dye and to study dyeing properties of the new dyes in application to nylon and a silk fabrics. The reactive disperse dye could be synthesized by the coupling reaction of diazotized 4-hvdroxyethylsulfone aniline with N-cyanoethyl-N-ethyl aniline and subsequent acetylation of the hydroxy group with acetic anhydride. The most appropriate pH for the dyeing of nylon fabric was 7 and suitable dyeing temperature was 80-100 "C. The build-up onto nylon fiber was good and various color fastnesses were good to excellent. The most appropriate pH for the dyeing of silk fabric was found to be 9. The build-up properties onto silk fiber were good, but the fixation was not as food as in the case of nylon fiber and various color fastnesses were generally good.good.