For use as an ion exchanger, a cationized nylon (EPTMAC-nylon) was prepared by reacting nylon-6,6 with epoxy propyl trimethyl ammonium chloride (EPTMAC), using anhydrous tin chloride (SnCl2) as catalyst in a nonaqueous medium. Evidence of grafting was provided by atomic force microscopy and the exchange capacity of EPTMAC-nylon was evaluated by potentiometric titration. The adsorption of four dyes (Acid Blue 25, Acid Yellow 99, Reactive Yellow 23, and Acid Blue 74) from aqueous solutions using a batch process was studied according to the adsorption capacity of the cationized support. The effect of experimental parameters such as dye concentration and adsorption temperature were analyzed. The adsorption isotherms were determined at different temperatures and modeled using Langmuir, Freundlich, and Jossens equations. (C) 2003 Wiley Periodicals, Inc.