A semi-empmcal expresslon IS proposed for the normal pulse polarographlc wave of the reduction of a metal ion m a labile metal-polyelectrolyte system, m the presence of an excess of hgand, and includes both the polyelectrolytlc hgand adsorption and the induced adsorptlon of the metal ion This expression avoids the need to know the values of the adsorption isotherms of both the complex and the polyelectrolytlc hgand as well as their time and potential dependences A non-hnear fittmg procedure 1s performed m order to obtam the parameters of the semi-empirIca expression, from which an appromate value of the stab&y constant of the complex can be estimated The accuracy of this sent-empmcal expression IS tested by simulated cmves, and It IS applied to expenmental results for the Cd(H)-polymethacrylate complex, m order to obtain the stab&y constant of the complex from expenmental data m the presence of adsorption phenomena Keywords Polarography, Adsorption, Metal-polyelectrolyte systems, Polyelectrolyte hgands A model has been recently proposed [1,2] for the mterpretatlon of the normal pulse polarographic (NPP) reduction of a metal ion m a labile metal-polyelectrolyte system, m the presence of an excess of hgand, and includes both the polyelectrolyte adsorptlon and the mduced adsorptlon of the metal ion This model has been applied to experunental data of the Cd(II)-polymethacrylate system [3,4]