To react with the cationic monomer, N-trimethylaminoethylmethacrylate chloride (TMAEMC), a beta-CD derivative carrying vinyl carboxylic acid groups (beta-CD-MAH)was designed and synthesized via esterfying reaction between beta-CD and maleic anhydride (MAH). Whereafter, a water-soluble amphoteric flocculant, the copolymer of TMAEMC and beta-CD-MAH (beta-CD-MAH-TMAEMC) has been synthesized by means of free radical copolymerization using the ammonium persulfate (APS) and sodium bisulfite (SBS) redox system as the initiator. The copolymer structure was demonstrated by FT-IR, H-1 NMR, SEM characterizations. Its excellent flocculated decolorization properties were evaluated with Acid Light Yellow 2G solutions using a jar test method. With the mass ratio of 1/10 (w/w) between the flocculant and dye, and at pH 4 and 20 degrees C of the initial dye solution, the maximum color removal reached. The charge neutralization played a dominant role during the flocculated decolorization process, although the inclusion of dye molecules into the cavities of beta-CD well maintained in side chain of beta-CD-MAH-TMAEMC also contributed to the conglomerates and floccules. (C) 2009 Elsevier B.V. All rights reserved.