The cadmium binding properties of a core-shell latex were investigated using differential pulse polarography. The latex particles have a polystyrene core which is surrounded by a hydrophilic shell containing a low density of sulphonic and carboxylic groups. For this core-shell latex dispersion, the binding of protons and metal ions can be analyzed reasonably well using Donnan's potential model [J.T. Davies and E.K. Rideal, Interfacial Phenomenon, Academic Press, New York, 1961]. However, the correction of Ohshima and Kondo [H.O. Ohshima and T. Konda, Biophys. Chem., 39 (1991) 181] of the Donnan model for the distribution of ions in the double layer near and in the shell is a real improvement. In this way, the binding constants of cadmium(II)with the surface groups of latex were separated into their intrinsic and electrostatic parts. The intrinsic constant for binding of cadmium(II) to carboxylic groups, obtained in this way, was similar to literature values.