In this work, response surface methodology (RSM) was employed to model and optimize electrodialysis process for mercury (Hg(II)) removal from seaweed extracts. Box-Behnken design (BBD) was utilized to evaluate the effects and the interaction of influential variables such as operating voltage, influent flow rate, initial concentration of Hg(II) on the removal rate of Hg(II). The developed regression model for removal rate response was validated by analysis of variance, and presented a good agreement of the experimental data with the quadratic equation with high value coefficient of determination value ( R 2 = 0.9913, R Adj 2 = 0.9678). The optimum operating parameters were determined as 7.17 V operating voltage, 72.54 L h −1 influent flow rate and 5.04 mg L −1 initial concentration of mercury. Hg(II) removal rate of 76.45% was acquired under the optimum conditions, which showed good agreement with model-predicted (75.81%) result. The results revealed that electrodialysis can be considered as a promising strategy for removal of Hg(II) from seaweed extracts.