Electrodialysis with two different configurations was used for the recovery of NaOH from the waste stream of a MEROX tower. For this purpose, the effects of cell applied voltage and initial Na+ concentration in the feed solution on NaOH recovery and current efficiency were studied. Results showed that the recovery and current efficiency were improved by increasing the initial Na+ concentration. Also, increasing applied voltage had different effects on current efficiency. A NaOH recovery of about 70% and a current efficiency of 98% for a three-compartment cell at 15 volts showed that the method can be considered as a promising one for NaOH recovery from the waste stream of a MEROX tower.