Abstract: The sorption of ⁶³Ni(Ⅱ) on γ-Al₂O₃ was studied by using batch technique. The effect of contact time, pH, ionic strength, γ-Al₂O₃ content and humic acid on the sorption of ⁶³Ni(Ⅱ) on γ-Al₂O₃ was investigated under ambient conditions. The results suggest that the sorption of ⁶³Ni(Ⅱ) is strongly dependent on ionic strength at low pH values, and independent on it at high pH values. The sorption of ⁶³Ni(Ⅱ) at low pH is mainly dominated by ion exchange and/or outersphere surface complexation, whereas the sorption of ⁶³Ni(Ⅱ) at high pH is mainly dominated by inner-sphere surface complexation. The presence of humic acid enhances ⁶³Ni(Ⅱ) sorption to HA γ-Al₂O₃ hybrids at low pH values, but reduces ⁶³Ni(Ⅱ) sorption to HA γ-Al₂O₃ hybrids at high pH values.