This study focused on the preparation of a thermal decomposition product of alunite and potassium chloride mixture as an adsorbent for the removal of phosphate ions from aqueous solutions. The adsorbed phosphate ions were quantitatively determined by using ion chromatographic method. The adsorption of phosphate onto adsorbent was strongly dependent on pH and on ionic strength. The optimum pH for the adsorption of phosphate was 3.0. Contact time was 40 min to reach adsorption equilibrium. The equilibrium data fitted well to Langmuir isotherm model. The thermodynamic parameters (Delta H-0, Delta S-0 and Delta G(0)) of phosphate adsorption at different temperatures calculated from the temperature-dependent adsorption isotherms indicated that the adsorption process was endothermic. The phosphate adsorption was also well applied in continuous system. (C) 2010 Elsevier B.V. All rights reserved.