Porous Co(OH) 2 film directly grown on nickel foam is prepared by a facile hydrothermal method. The as-prepared Co(OH) 2 film possesses a structure consisting of randomly porous nanoflakes with thicknesses of 20-30 nm. The capacitive behavior of the Co(OH) 2 film is investigated by cyclic voltammograms and galvanostatic charge-discharge tests in 2 mol/L KOH. The porous Co(OH) 2 film exhibits a high discharge capacitance of 935 F g −1 at a current density of 2 A g −1 and excellent rate capability. The specific capacitance keeps a capacitance of 589 F g −1 when the current density increases to 40 A g −1 . The specific capacitance of 82.6% is maintained after 1500 cycles at 2 A g −1 . Pseudocapacitive materials, such as transition metal oxides/hydroxides and conducting polymers, are being explored for producing supercapacitors with increased specific capacitances (several times larger than those of carbonaceous materials) and high energy densities [2−6]. RuO 2 -base electrode materials are well studied as pseudocapacitive electrode materials with remarkable performance (760 F g −1 for a single electrode system) [7]. However, apart from being toxic, RuO 2 is quite expensive for extensive commercial applications. Therefore, great efforts have been devoted to searching for inexpensive alternative transition metal oxides/hydroxides materials with good capacitive characteristics [8−17]. Co(OH) 2 is an attractive pseudocapacitive material because of its high specific capacitance, well-defined electrochemical redox activity, and low cost [14,15]. A nano-level whisker-like Co(OH) 2 powder was fabricated by Yuan's group [15] and showed excellent electrochemical performance. On the other hand, it is well accepted that pseudo-capacitance is an interfacial phenomenon tightly related to the morphology of electroactive materials. The porous structure could provide a very short diffusion pathway for ions as well as large active surface area, leading to enhanced electrochemical properties [2,3,5]. Compared to powder, the film structure materials have good conductivity under the same conditions.In the present work, the porous Co(OH) 2 nanoflake film on nickel foam is prepared by hydrothermal method. Remarkably, the as-prepared film exhibits superior performances with excellent capacity retention and high specific