Adsorption isotherms of nitrates on the resin Amberlite IRA 410 at various pH values (6.8-12) were experimentally determined by batch tests. Six models involving two or three parameters are discussed. Concerning the Langmuir equation, the linear method had no significant effect on the estimation of isotherm parameters and simulation precision. Irrespective of the pH, the Sips model was found to give the best fit of the adsorption isotherm data. The maximum adsorption capacity decreased with increasing pH values and could be predicted by the correlation equations obtained in this study.