Flower-like hydrotalcite-based NiAl mixed oxides with high surface area were synthesized by urea hydrolysis approach, and employed for SO2 removal. The catalyst was well characterized by TGA, XRD, SEM, TEM and N-2 adsorption/desorption isotherm analyses. The calcined NiAlO showed excellent SO2 adsorption and its adsorption equilibrium was of a type I isotherm, which significantly improved the adsorption performance for low-concentration SO2. XPS and TPD methods were conducted to identify the sulfate species. Specifically, in situ Fourier transform infrared spectroscopy revealed that adsorbed SO2 molecules formed surface bidentate binuclear sulfate. Density functional theory based computations interpreted the vibrational data associated with the NiAlO surface and confirmed that sulfate species adopted a binuclear bidentate binding configuration on the surface of NiAlO catalyst. (c) 2012 Elsevier B.V. All rights reserved.