A film of deeply oxidized graphene oxide is used for the first time as a separator of a supercapacitor. The supercapacitor fabricated possesses a layer PANi/GO/PANi structure, where PANi is polyaniline and GO is graphene oxide. The capacity of this supercapacitor is about 150 F per gram of the total weight of the electrode, separator, and electrolyte (1 M H2SO4). Our data do provide evidence that the GO film has a proton type conductivity after being permeated with a solution of sulfuric acid. Published by Elsevier B.V.