Technical Abstract: The presence of fiber-reactive dye hydrolysis products in dyehouse effluents poses a difficult wastewater treatment problem. Although conventional ion-exchange resins can be used to remediate reactive dye-containing effluents, regeneration of resin exchange capacity can require use of organic solvents, which substantially increases the cost of the treatment process. The present study demonstrates that quaternized cellulose can remove effluent reactive dye hydrolysis products, largely unhindered by typical dyebath concentrations of electrolytes. Furthermore, the dye adsorption capacity of the quaternized cellulose can be regenerated by base treatment (aqueous NaOH). Thus, quaternized cellulose could be economically employed for decolorization of dyehouse wastewater.