We demonstrated that the morphology and textural property of gamma-AlOOH can be tuned by modulating the alkyl chain length of cation in [C(n)mim]Cl-+(-) (n = 4, 8, 16). Using the short alkyl chain length-based [C(4)mim]Cl-+(-) as the structure-directed reagent, the morphology of gamma-AlOOH was not changed and preserved as the hollow sphere structure in all experiments. The specific area and the number of small meso-pores of gamma-AlOOH increased with the increase of [C(4)mim]Cl-+(-) dosage. While, using the larger alkyl chain length-based ionic liquids as the soft-template, such as [C(8)mim]Cl-+(-) and [C(16)mim]Cl-+(-), the morphologies of gamma-AlOOH were changed from initiative hollow spheres into the final microflowers. The specific areas of gamma-AlOOH firstly increased then decreased with the increase of their dosage. The samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). Furthermore, the possible formation mechanisms of gamma-AlOOH have been proposed. (C) 2013 Elsevier Ltd. All rights reserved.