The effect of operating condition on the performance of new type of PVDF-SiO2 organic-inorganic ion-exchange membranes used in electrodialysis process was investigated with single salt solution in comparison to PVDF membranes. The experimental results indicated that better transport properties of PVDF-SiO2 membranes may be responsible for the limited current density (LCD) of the membranes higher than that of PVDF membranes. The LCD values of PVDF-SiO2 and PVDF membranes at NaCl solution of 5000 mg/L were 1.43 mA/cm(2) and 1.13 mA/cm(2), respectively. In addition, desalination ratio increased with increasing current density and feed flow rate. It was also found that at the optimum operating condition, the removal ratios of Na+, Ca2+, Cl- and SO42- by electrodialysis employing PVDF-SiO2 membranes were 97.7%, 93.5%, 96.5% and 88.5%, respectively, and the removal ratios of the ions in the presence of PVDF membranes were 91.4%, 88.4%, 92.5% and 85.7%, respectively. It can be concluded that these PVDF-SiO2 organic-inorganic ion-exchange membranes with better membrane properties can be used in electrodialysis process. (C) 2012 Elsevier B.V. All rights reserved.