Binder-free Ni(OH)(2)/carbon nanofiber composites used as supercapacitor electrodes were fabricated through the chemical precipitation of Ni(OH)(2) on electrospun carbon nanofibers. These composites exhibited a hierarchical structure in which Ni(OH)(2) nanoflakes connected with the carbon fiber network. We varied the annealing temperature to investigate the morphological progress and the subsequent electrochemical performance of the composite fibers. The hierarchical structure remained unchanged when the annealing temperature was lower than 300 degrees C. At 350 degrees C, most Ni(OH)(2) was converted to NiO, and NiO peeled off from the fiber surface, forming NiO microparticles. Electrochemical measurements revealed that the specific capacity of the Ni(OH)(2)/carbon nanofiber composites increased with an increase in the annealing temperature and reached a maximum of 455 degrees C/g at 300 degrees C. in addition, the Ni (OH)(2)/carbon nanofiber composites exhibited a favorable cycling stability after 2000 cycles without fading. The electrochemical performance of the composites was satisfactory because of the synergetic effect of the faradaic behavior of Ni(OH)(2) and easily accessible electron transport in the carbon nanofiber network. At 350 degrees C, the peeling off and aggregation of NiO microparticles caused a reduction in the specific capacity of the Ni(OH)(2)/carbon nanofiber composites. (C) 2015 Elsevier Ltd. All rights reserved.