In this work, we first investigate theoretically the pressure-induced potential arising across the active layer of a membrane. It is shown that this potential, called the filtration potential, firstly varies sublinearly and then becomes a linear function of permeate volume flux (J(v)). The sublinear behavior is due to the occurrence of membrane potential resulting from the concentration difference across the active layer. When the concentration difference tends to saturation, the membrane potential becomes constant and the variation of the filtration potential with J(v) therefore results only from the dependence of the streaming potential on J(v), A linear behavior is then obtained. It is found that the magnitude of the filtration potential increases with thickness to porosity ratio, volume charge density (X) and decreasing pore size. It is also shown that the streaming potential coefficient becomes independent of the volume charge from low values of X and decreases with decreasing pore size. Further on, we investigate the electrokinetic properties relative to both active and support layers of a low UF composite ceramic membrane from filtration potential and ionic rejection rate measurements. The values of X for the active layer are firstly calculated from experimental rejection rates and then used to compute the filtration potential through the active layer. The extrapolation of linear parts to zero J(v), allows to determine the transport numbers of ions within the active layer. Filtration potential measurements performed through the whole membrane show that the support layer makes an important contribution. After the subtraction of the active layer contribution, the streaming potential coefficient of the support can be then obtained. (c) 2005 Elsevier B.V. All rights reserved.