Abstract: Water soluble disperse dyes of either monoazo or anthraquinone types containing the carboxymethylsulfonylgroup(-SO_2CH_2COOH)were synthesized.Ammonium salts of this type of dyes are more soluble thanother salts.These dyes are suitable for pad dyeing or printing on polyester fiber and polyester/cottonblends in either weak acid,neutral or weak alkali medium without a dispersing agent.The formation of-SO_2CH_3 group from -SO_2CH_2COOH group after fixing on the fiber was proved.