The mesoporous MgO nanosheets were obtained using Mg(NO3)(2)center dot 6H(2)O and urea as the raw materials without any surfactant via hydrothermal and calcination method. The effect of annealing temperature on the nanostructures and the adsorption performance were reported. The MgO annealed at 600 degrees C were mesoporous nanosheets with surface area of 45 m(2)/g. More interestingly, it exhibited high-rate adsorption property of Ni (II) with a removal efficiency up to 99.99% in 15 min and a maximum adsorption capacity of 885 mg/g. (C) 2016 Elsevier B.V. All rights reserved.