A simple and novel process has been proposed to synthesize alumina using gardenia extract and aluminum salts in an aqueous solution. The alumina sample notated as "bio-Al2O3" was characterized by X-ray diffraction (XRD) and nitrogen adsorption-desorption experiment. The results indicated that the existence of the gardenia biomass enlarged the surface area of alumina and reached 256 m(2)/g. The thermo gravimetric (TG), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) results showed that gardenia biomass bound to the surface of the alumina has substantially improved the adsorption capacity of Ni(II) and the adsorption behavior of nickel ion was related to the biomass functional groups. The results of three adsorption-desorption cycles showed that the bio-Al2O3 using as the adsorbent for Ni(II) was relatively stable. The kinetic of the Ni(II) adsorption by the bio-Al2O3 followed pseudo-second-order equation. Langmuir and Freundlich isotherm models were applied to analyze the experimental data and the result demonstrated that the adsorption isotherms followed Langmuir isotherm model. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.