AbstractAdsorption experiments were conducted by mixing NaCl‐kaolinite and C14‐labelled hydrolyzed polyacrylonitrile (HPAN) in water solutions of various electrolytes. An increase in the concentration of electrolyte caused an increase in extent of HPAN adsorption, the effect apparently being due to reduction of electrostatic repulsion between HPAN and kaolinite and reduction in size of the HPAN coil. Divalent cations, especially the transition metals capable of being complexed, were more effective than univalent cations. Maximum adsorption took place in the presence of H+ ions.Anions capable of complexing lattice aluminum and/or decomposing the clay crystal reduced adsorption of HPAN. There was some evidence of competition for adsorption sites.