The response surface methodology (RSM) was used in this work to develop an optimum membrane for micellar-enhanced ultrafiltration (MEUF). The mixed-matrix membranes were prepared by adding TiO2 nanoparticles into polyvinylidene fluoride (PVDF) solution and cast at different thicknesses. Flat-sheet PVDF membranes were prepared via the phase inversion technique on the basis of central composite design (CCD). The objective function of the optimization is to prepare membrane with high rejection and flux for micellar enhanced methylene blue (MB-SDS) ultrafiltration. The interactive effects of the various parameters, namely polymer concentration, membrane casting thickness and TiO2 concentration towards rejection of MB-SDS and permeation flux were evaluated. CCD was employed to obtain the mutual interaction between the various parameters. The optimum membrane could be prepared under polymer concentration of 18 wt.%, casting thickness of 400 mu m and TiO2 concentration of 1.62 wt.%. The experimental value of permeation flux and rejection was 53.28 +/- 2.75 L/h.m(2) and 99.02 +/- 0.55%, respectively. These values were found to be in good agreement and very close to the optimized value predicted from CCD, which were 57.68 L/h.m(2) and 98.77%. The results show that process optimization using CCD was reliable to produce membrane with desired performance. (c) 2012 Elsevier B.V. All rights reserved.