Highly uniform three-dimensional alpha-Ni(OH)(2) hierarchical architectures based on nanoslices were successfully synthesized on a large scale in a water-in-oil microemulsion of cetyltrimethylammonium bromide (CTAB)/water/cyclohexane/glycerol with Ni(HCOO)(2)center dot 2H(2)O served as both a nickel source and a weak alkaline source. The phase formation of alpha-Ni(OH)(2) takes advantage of the hydrolyzation of HCOO- in Ni(HCOO)(2)center dot 2H(2)O precursor. The size and morphology of alpha-Ni(OH)(2) can be tuned through varying the experimental parameters. As-obtained 3D alpha-Ni(OH)(2) possesses high electrochemical sensitivity to H2O2, and the microstructures had a noticeable influence on their sensitivities, which indicate potential applications in the field of electrochemical sensing devices. (C) 2013 Elsevier Ltd. All rights reserved.