Chemical modification of graphene nanosheets by KOH was examined as a way to enhance the specific capacity of graphene nanosheets in supercapacitor. Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy were used to investigate the effects of the treatment on the surface of the graphene nanosheets. The specific capacitance of 136 Fg(-1) was obtained for KOH treated graphene by integration of the cyclic voltammogram, an increase of about 35% compared with that for the pristine graphene nanosheets. (C) 2011 Elsevier B.V. All rights reserved.