In the present work, Colloid-Enhanced Ultrafiltration (CEUF) was investigated using complexes formed by sodium dodecyl sulfate (SDS) and hydroxypropylcellulose (HPC) to test the performance of removing o-cresol (0.1 mM) from dilute aqueous solutions. In order to study CEUF, stirred-cell experiments were conducted and a dye solubilization method was employed. The results showed that the critical aggregation concentration (c.a.c) of SDS was about 2 mM for the HPC/SDS/water system. When the proposed system was employed for removing o-cresol, CEUF required very small surfactant concentrations, about 10% of the SDS concentrations normally used in MEUF. In addition, the rejection and permeate flux are strong functions of [SDS] and it is necessary to find the optimum SDS concentration when operate CEUF.