The removal of fluoride from aqueous solution with plasma-modified and unmodified poly(2-chloroaniline) (P2C1An) anion-exchange membranes were studied by Donnan dialysis (1313). The effects of concentration, pH, and different valence anions on feed phase were investigated. The surfaces of P2C1An membranes were modified by electron cyclotron resonance plasma (ECR) to increase the performance. The flux values of fluoride before and after the modification were obtained. An increase of fluoride flux has been observed with increasing concentration of the feed phase. Also, the flux value for the plasma-modified P2C1An membrane was found to be higher than that of the unmodified membrane. This can be explained by a wider and increased number of pores in the plasma-modified membrane. In addition, effects of different valence anions on flux of fluoride were studied and found as Cl-> SO42-. The pH optimization was carried out between 3-9 and pH 5.5 used for all experiments.