In this work, a new surface active site (SAS) adsorption equilibrium model was presented, which explicitly accounted for the H+ competitive adsorption with Ni2+ in adsorption equilibrium. Static adsorption experiments with Ni2+ as a model metal ion were carried out to determine the model parameters, those were, equilibrium constant for Ni2+ (K-a), for H+ (K-s), characteristic number of binding sites for Ni2+ (n), for H+ (a), and the non-imprinted factor (sigma). It was found that those model parameters n and a were all constant, and that they all expressed that one active site bound two Ni2+ or two H+, while the non-imprinted factor, sigma, was effected by Ni2+ concentration, H+ concentration in solution and imprinted Ni2+ concentration in the preparation. Simulated result was compared with experimental data of the adsorption for Ni2+. It was showed that this model could be well used to predict the adsorption equilibrium for Ni2+ on the surface imprinted adsorbent. And it was demonstrated that the efficacy of the active sites formalism could be used in describing adsorption behavior for Ni2+ on the surface imprinted adsorbent. (c) 2007 Elsevier Ltd. All rights reserved.