Membrane fouling weakens seriously the membrane's separating performance, which can be reduced by the membrane surface modification. Commercial Al2O3 microfiltration membranes were modified by the nano-sized ZrO2 coating to reduce the membrane fouling by oil droplets and to keep the unique character of the inorganic membrane. The nano-sized ZrO2 coating is prepared by in situ hydrolysis of ZrCl4. The results show that the nano-coating does not form a separating layer, and just makes the ceramic membrane more hydrophilic. Using the stable 1 g/L 20(#) engine oil-water emulsion as feed, the steady flux of the modified membrane is obtained in a very short time. The steady flux keeps 88% of the initial flux and the oil rejection is above 97.8%. The hydrophilic nano-sized coating, the backflushing and the appropriate cross-flow velocity contribute to reducing the membrane fouling by oil droplets. The modified membrane has the good performance in the oil-water separation of stable emulsions. (C) 2010 Elsevier B.V. All rights reserved.