Silica-filled polydimethylsiloxane (PDMS) composite membranes are prepared on a polytetrafluoroethylene support structure. The structure and the performance of the membranes are characterized by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetry. The pervaporation process for acetic/water separation is performed within the PDMS membranes. The vulcanization temperature was found to have a great influence on the separation performance of the membrane. The addition of silica can significantly improve the pervaporation flux and enhance the thermal stability of the membrane. With an increase in the feed temperature, selectivity decreases and permeation flux increases. Performed with a pure PDMS membrane vulcanized at 30 degrees C, the separation factor at first will increase, then decrease when the feed flow rate was increased from 14 to 38 L . h(-1). The maximum separation factor is achieved when the feed flow rate is 26 L . h(-1). POLYM. ENG. SCI., 51:819-825, 2011. (C) 2011 Society of Plastics Engineers