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The adsorbent ability of Al2O3 nanoparticles (ANPs) was examined to remove Cd2+ and Zn2+ from aqueous solution. The sorption of Cd2+ and Zn2+ on ANPs as a function of pH, ionic strength (IS), humic acid (HA), contact time, foreign ions and the temperature were investigated. It was observed that physico-chemical factors (pH and ionic strength) strongly affect the sorption of Cd2+ and Zn2+ on ANPs. Comparatively, the sorption of Cd2+ and Zn2+ dominated by surface complexation of the outer sphere at low pH values (pH < 8.0), while surface complexation of the inner sphere was the major sorption mechanism at elevated pH values (pH > 8.0). The maximum sorption capacity of Cd2+ and Zn2+ on ANPs calculated from the Langmuir model was 8.40 and 9.00 mg g–1 respectively at 303 K, exhibiting higher efficiency for Zn2+ sorption than Cd2+.The thermodynamic parameters (∆H0, ∆S0 and ∆G0) showed that the adsorption of Cd2+ and Zn2+ was endothermic and spontaneous. This investigation exhibited that ANP is an efficient, inexpensive process and thereby reasonable technology for the elimination of metal ions from the contaminated aqueous source. [ABSTRACT FROM AUTHOR]