Polysulfone membranes on a cellulose support were obtained by phase inversion, directly on the carrier's surface. The membranes were obtained by the continuous method by means of a special device. Cellulose was dissolved in order to study the real membrane thickness and estimate the depth of polymer penetration into the cellulose matrix. Thickness measurements of the membranes were carried out and their high uniformity was found. The permeation times for the membrane alone and for the membrane on a support have been compared. It was found that the sum of times of permeation through a cellulose support and through a membrane deprived of a support is always shorter than that through a membrane and support together. For one thickness assumed as optimal, the dependence of time of permeation through a membrane and support for different compositions of membrane-forming mixtures was studied. The membrane-forming mixture contained always the same concentration of the basic polymer and the same concentration of the pore-precursor additive. Polyvinylpyrrolidones (PVPs) of various molecular weights, both alone and as mixtures of two PVP of different molecular weights, were used as pore-precursors for obtaining these membranes. It was found that the shortest times of permeation through the studied membranes are obtained when equal weigh amounts of PVP of different molecular weights are used as the additive to polysulfones. It was found that the membrane for which an equilibrium PVP mixture of 10 and 60 kDa molecular weight was used as the pore-precursor, which is best suitable for dry tests. Such membranes are especially well suitable for obtaining dry tests for the analysis of fruit and vegetable juices. (C) 2008 Elsevier B.V. All rights reserved.