A low-cost, hydrophilic ceramic-polymeric composite membrane was prepared from clay (collected from the bank of river Ganges), kaolin and small amount of binding materials. The support was prepared by paste casting whereas the composite membrane was prepared by dip coating with 10% cellulose acetate (CA) solution in acetone (w/v) with 60 s dipping time. The ceramic support was characterized by TGA, SEM, XRD, water permeability test and acid-base treatment and the composite membrane was characterized using SEM and pure water flux. A novel theoretical method was proposed for determination of the porosity and average pore size of the polymeric layer. Mass of the CA film, thickness of the polymeric layer, hydraulic permeabilities of the support and composite membrane were used for the theoretical derivation. The porosity and effective pore size of the composite membrane were found to be 0.56 and 28 nm. The prepared composite membrane was used to treat an oil-in-water emulsion containing 50, 100 and 200 mg L(-1) oil. For all the initial oil concentrations, rejection increased with time whereas rejection was higher for high oil concentrations. Maximum rejection observed was 93% with a permeate oil concentration of 14 mg L(-1) V at 138 kPa. (C) 2011 Elsevier B.V. All rights reserved.