The aim of the present research is the electrokinetic determination of the inner surface centercharges of ceramic nanofiltration membranes under varying electrochemical conditions and their influences on the filtration properties especially on salt/ion rejection. Ceramic microporous nanofiltration membranes of TiO2 with pore size of 0.9 nm were characterized. The membrane charge was determined under real filtration conditions at different salt solutions, concentrations and pH-values using flow-through streaming potential measurement. In the case of liquid saturated oxide ceramic membranes a surface charge results from protonated and deprotonated surface groups and specifically adsorbed ions. The charge properties of the amphoteric titania nanofiltration membrane significantly depending on the pH value of the feed. The specific adsorption of multivalent ions modifies additionally the membrane charge and shifts the isoelectric point. Depending on the valence and art of the ions and the pH value/range of the solution the membrane charge is shielded or increased. Using magnitude and sign of the measured streaming potential at different salt solution, concentration and pH-values the salt/ion rejection can be predicted. This could be checked by cross-flow filtration experiments. Single and multivalent ion separation in the nanofiltration range does not only result from a sieving effect/steric exclusion of the pore structure but is strongly influenced by the surface charge characteristics of the pore/channel walls. When the membrane is charged, the ions are retained, and when shielded, the ions pass through the membrane. The investigations show the possibility for adjusting the separation characteristic up to a nearly complete salt rejection by choosing the appropriate pH-value, concentration and the kind of the salt solution. The measurement of the streaming potential during real filtration processes supports in the simplest way the optimization and monitoring of desalination processes with charged nanofiltration membranes.