Poly([(2-methacryloyloxy)ethyl]trimethylammonium chloride) resin, P(MOTA) was successfully synthesized by radical polymerization. The resin was characterized by FTIR and SEM. Parameters including the water absorption capacity, effect of the pH, maximum retention capacity of the metal ions, elution, regeneration, adsorption rate, and adsorption isotherms were studied. All the studies were carried out by batch equilibrium procedure. The changes of thermodynamic parameters such as enthalpy, entropy, and free energy were calculated. The P(MOTA) resin showed higher capacity to remove As(V) from water solution than that Amberlite IRA-400(Cl) commercial resin. The higher capacity displayed by P(MOTA) resin was attributed to the higher degree of swelling and different structure than Amberlite IRA-400(Cl).