The charge of ceramic UF membranes is studied in NaCl and CaCl2 media from streaming potential and membrane potential measurements. The amphoteric behaviour of these materials is observed with both methods. The apparent transport numbers of cations in the membrane are determined from cell potential measurements. Streaming potential measurements and the study of the transport properties lead to similar isoelectric points of the membrane. It also appears that the presence of Ca2+ cations leads to a more positive net charge of the membrane at pH lower than the isoelectric point and a less negative charge for the higher pH.