The micellar-enhanced ultrafiltration (MEUF) process for obtaining pure water from aqueous solutions containing small amounts of toxic organics such as phenol and benzene has been studied. A homologous series of polyethyleneglycol alkylether having different numbers of methylene groups and oxyethylene groups was used for nonionic surfactants. Cellulose acetate and polysulfone membranes having different molecular weight cut-offs (MWCO) were used as hydrophilic and hydrophobic membranes, respectively. The performance of the MEUF process in removing organics was shown to depend on membrane characteristics, surfactant characteristics, organic characteristics, and operating conditions. The decline in the permeate flux with polysulfone membranes was serious, while that with cellulose acetate membranes was not remarkable. The rejection of organics increased with increasing hydrophobicity of surfactant when the feed solution contained the same amount of surfactant. The rejection of organics for the cellulose acetate membrane increased with decreasing membrane pore size and with increasing operating pressure. On the other hand, the rejection behavior of organics for polysulfone membranes was shown to depend on the characteristics of organics. The rejection behavior of phenol was also similar to that for cellulose acetate membrane, while that of benzene was totally different from that for the cellulose acetate membrane. Benzene rejection for polysulfone membranes decreased with increasing operating pressure and with decreasing pore size. Regardless of membrane characteristics, benzene was more effectively removed than phenol via the MEUF process. The performance of MEUF could be explained with the solubilization behavior of organics and hydrophobic interactions.