The retention of neutral solutes and ionic solutions on a NF ceramic membrane was measured. The Donnan Steric Pore Model (DSPM) was fitted to these observations yielding effective pore radius (r(p)) and thickness/porosity ratio (Deltax/A(k)) from neutral solutes data and the effective volume charge (X) from electrolyte data. Effective volume charges were also directly determined using tangential streaming potential measurements. The DSPM gives X in good agreement with the values obtained by streaming potential. However, it overestimates Deltax/A(k) compared to the value deduced from neutral solute retention.