Novel hydrophilic SiOx modified alumina membranes with high separation factors and flux rates have been prepared for the separation of water from organic solvents. For the preparation of the membranes, SiOx networks are deposited inside the gamma-Al2O3 layer of a commercial ultrafiltration membrane by hydrolysis of tetraethylorthosilicate in autoclaves at 250degreesC. The transport resistances of the individual membrane layers for the permeation flux are described by a model. The membranes are stable towards solvents to temperatures of at least 150degreesC. Pervaporation studies show that water can be separated from solvents such as acetonitrile, tetrahydrofurane, 2-propanol, ethyl alcohol, dimethylsulfoxide, N,N-dimethylformamide, and phenol. The separation performance of the membranes allows their use in technical separation processes, especially for the removal of water.