Polypyrrole/carbon nanotube (PPy/CNT) composites were prepared via chemical oxidation method. By choosing sodium dodecyl benzene sulfonate (SDBS) as the dopant in the preparation process, the obtained composites have the ability of selective adsorption for cations and are suitable for application as the cathode material of capacitive deionization cell. The scanning electron microscope and transmission electron microscopy analysis showed that the PPy/CNT composites were in nanotube morphology with the CNTs wrapped uniformly by the PPy layer. Electra-chemical characteristics and desalting performance of PPy/CNT composites were tested and analyzed. The results indicated that specific capacitance of PPy/CNT composites increased more than 3 times compared with the CNTs. The saturated adsorbing capacity of PPy/CNT-CNT cell (PPy/CNTs used as cathode) was evaluated as 43.99 mg/g, which is much higher than that of CNT-CNT cell (about 11.00 mg/g). So the PPy/CNT composites doped with DBS- have a great potential as the high-performance cathode material for capacitive deionization technology. (C) 2014 Elsevier B.V. All rights reserved.