Biofouling control in the polyamide RO membrane process has been restricted since the membranes are vulnerable to chlorine which is an effective disinfectant for water treatment. Chlorine eventually decreases salt rejection and shortens membrane life expectancy. This study investigated dichloroisocyanurate (DCC) for biofouling control in polyamide RO membrane process which could be employed to be a CIP agent or a disinfectant in pretreatment. The evaluation of DCC consisted of membrane performance tests and antimicrobial effect in comparison with those of chlorine under the identical conditions. Permeate flux, salt rejection, and surface characterization were examined as membrane performance indicators after exposure to disinfectants. The antimicrobial effect of DCC was investigated on biofilm grown on membrane surface. The results showed that normalized salt rejections of DCC-exposed membranes were stably kept at 99% without the sacrifice of flux, while those of chlorine-exposed membranes decreased to 80%. The biofilms grown on RO membrane were inactivated by DCC as much as chlorine. This study suggests the excellent possibility of DCC usage for biofouling control in RO process. (C) 2012 Elsevier B.V. All rights reserved.