Adsorption of La(III) and Ce(III) from aqueous solutions by novel chitosan modified with poly(vinyl alcohol) as a promoter of mechanical and chemical properties and 3-mercaptopropyltrimethoxysilane as a promoter of the functional group was investigated in batch and continuous modes. The FTIR analyses showed that mecapto groups have been successfully added to chitosan/poly(vinyl alcohol). The BET surface area, pore diameter, and pore volume of adsorbents were 1.68m(2) g(-1), 2.516nm, and 0.058cm(3) g(-1), respectively. The effects of the operating parameters such as pH, contact time, initial metal ion concentration, adsorbent dosage, and temperature were studied in batch mode operation. Optimum pH was found to be 5. According to the Langmuir model, the maximum adsorption capacities for La(III) and Ce(III) ions were 263.16 and 251.41mgg(-1), respectively. The thermodynamic study showed that the adsorption process of both metal ions was endothermic and spontaneous favored at the higher temperature. In the column study, the effects of the flow rate and initial concentration were investigated. The maximum adsorption capacities based on the Thomas model for La(III) and Ce(III) ions were 460.94 and 374.83mgg(-1) at a flow rate of 4mL min(-1) and an initial metal concentration of 300mgL(-1), respectively.