A method of deconvolution has been developed to determine the site-specific selectivity coefficients for divalent and trivalent exchange in relatively rigid exchangers. The technique involves the measurement of ion-exchange isotherms and the application of the numerical approach of regularization to effect deconvolution. The method has been designed and extensively tested with computer-generated isotherms. The results of these numerical studies indicate that this approach can successfully recover selectivity coefficient distributions from divalent and trivalent isotherms. If a careful accounting of the exchanging cations is maintained, this method can be applied to systems undergoing ion exchange by different mechanisms.