Zeta potential and electrokinetic surface charge density for membranes with different structures and materials (cellulose, polyamide and polysulfone) were determined from tangential streaming potential measurements carried out with different electrolytes (NaCl, NaNO₃, and CaCl₂ solutions). Differences in ζ values were obtained for the same membrane depending on the electrolyte used, while the zeta potential-concentration relationship also depends on the membrane considered. Two different adsorption mechanisms were assumed for cellulose and polysulfone membranes (Langmuir and Freundlich adsorption, respectively) and different characteristic adsorption parameters were determined (molar Gibb free energy of adsorption, density of accessible sites,…). Dissociation constant and density of acid sites were determined for polysulfone and polyamide membranes from zeta potential-pH dependence assuming a dissociation model. Surface chemical modification (hydration) of the polyamide membrane determined from X-ray spectroscopy analysis has been correlated with variations in the electrokinetic parameters.