The effect of ion beam irradiation on the performance of two commercial water treatment membranes was studied. The results of this testing indicate that the irradiation induced structure modifications had a positive impact on the membranes application to wastewater treatment. Irradiation of the first membrane (TFC-S, Koch Membrane Systems, San Diego, CA) led to a slight decrease in selectivity, but this was outweighed by the positive effects of the irradiation. Not only did the irradiation improve both abiotic and biofouling resistance, it also doubled the membrane solvent mass transfer coefficient (MTC). Ion beam irradiation also improved the performance of the second membrane (NTR 7450, Hydranautics, San Diego, CA). Water quality testing revealed similar removal of contaminants, while fouling tests indicated an improvement in the membrane's resistance to fouling, especially in the case of biofouling.