It is desirable to apply a disinfectant for biofouling control in the membrane elements as well as in the intake system of seawater reverse osmosis (SWRO) plants. Chlorine dioxide (ClO2) would be an ideal candidate, since it is a highly effective disinfectant, does not produce chlorinated disinfection by-products, and as a dissolved gas it easily passes the membrane, allowing disinfection of the permeate side. Compared to chlorine and chloramine, ClO2 is a less aggressive oxidant, however, it has a higher oxidizing capacity. Polyamide membranes are known to be easily damaged by oxidants, and the potential for membrane damage is hampering the application of ClO2 in reverse osmosis. The presence of bromine, relatively high pH and high temperature, suggests that in Middle East, it is a serious possibility that membrane damage occurs in SWRO. Conversely, it is highly likely that ClO2 dosing is effective against biofouling, since it is an effective disinfectant and it can easily be transported into the biofilm and through the membrane.