The Ni(OH)(2) architectures with flower-like morphology assembled from nanosheets have been successfully synthesized through a microwave-assisted hydrothermal method using urea as a hydrolysis-controlling agent and polyethylene glycol (PEG) as a surfactant. The NiO architectures with similar morphology were obtained by a simple thermal decomposition process of the precursor Ni(OH)(2). The as-obtained products were well characterized by XRD, TG-DTA, SEM, TEM, FTIR and UV-Vis. The experimental results shown that flower-like Ni(OH)(2) architectures with a diameter of 2.5-4.0 mu m are assembled from nanosheets with a thickness of 10-20 nm and width of 0.5-1.5 mu m. The UV-Vis experimental results shown that the absorption edge of the NiO architectures have a blue-shift with the increasing of the calcination temperature. (c) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.