A three-dimensional (3D) nanoporous NiO film was fabricated via a two-step process using an electrochemical route. This process included electrodeposition of the Ni/Zn alloy film and electrochemical dealloying using a direct-current power source. The scanning electron microscopy images suggest that the film has an irregular 3D interconnected nanosheet structure with open channels. The adsorption-desorption isotherms indicate that the as-prepared NiO film had a high specific surface area of 198 m g(-1) and a narrow pore size distribution, with two peaks at 2.7 and 5.1 nm. The specific capacitance of the sample reached 1670 F g(-1) at a discharge current density of 1 A g(-1). In addition, the as-prepared nanoporous film exhibited high performance during a long-term cycling test. The maximum values for the specific energy and specific power at the 1.1 V potential window were 170 and 27.5 kW kg(-1), respectively. (c) 2013 Elsevier Ltd. All rights reserved.