Porous hierarchical Ni(OH)(2) composed of petal-like nanosheets with a mix of alpha-and beta-phase was synthesized via a facile hydrothermal method using urea as precipitating agent. In order to tune the pore properties and optimize phase compositions of Ni(OH)(2), different types of alcohols (methanol, ethanol, ethylene glycol and glycerol) were added into the hydrothermal systems. It was found that the addition of methanol would retain the porous hierarchical structure of Ni(OH)(2), enlarge the pore size and volume, make the transformation of beta phase to at phase. However, other alcohols (ethanol, ethylene glycol and glycerol) would destroy the porous hierarchical structure and have little impact on the phase transformation. Using the as-prepared samples as adsorbents for the removal of Congo red (CR), Ni(OH)(2) synthesized in methanol aqueous solution exhibited excellent adsorption performance than other samples. When the volume ratio of methanol to water is 1:1, the as-prepared Ni(OH)(2) (Ni(OH)(2)-m1/1) exhibited best adsorption capacity. The adsorption kinetics fitted well with the pseudo-second-order kinetic model of Ni(OH)(2)-m1/1. Equilibrium data were best described by Langmuir model. The estimated maximum adsorption capacity of Ni(OH)(2)-m1/1 for CR was 206.2 mg/g, making it a promising candidate for wastewater treatment. (C) 2017 Elsevier B.V. All rights reserved.