The influence of BSA on adsorption equilibrium of Ni2+ onto delta-MnO2 had been investigated using a batch method. It was showed that the adsorption-pH curves of Ni2+ onto delta-MnO2 were "S-shape" at [BSA] = 10 mg x L(-1), and the leaping range of adsorption would move to high value of pH in the presence of BSA. The extent of effect had relation to the adding order and the concentration of BSA, and the trend was IV (BSA added first) > III (Ni2+ and BSA added simultaneously) approximately II (Ni2+ added first). The adsorption percentage decreased with increasing BSA concentration at the same value of pH. The Langmuir adsorption model fit the experimental date reasonably in the presence of BSA. The maximum adsorption capacity related to the BSA adding order was I (without BSA) > II approximately III > IV. In addition, the adsorption of Ni2+ onto delta-MnO2 increased with the rise of temperature. It was found that the adsorption was irreversible at pH = 4.0 and pH = 7.0. BSA had no effect on the reversibility of Ni2+ adsorption onto delta-MnO2.