A systematic investigation of the graphene oxide composite reduced by either p-phenylenediamine oligomers or hydrazine hydrate was performed with field emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, fourier transform infrared, and X-ray photoelectron spectroscopy analyses. The electrical capacitance of the composite was evaluated by a cyclic voltammetry technique, while the properties of these prototype supercapacitors were measured by a chronopotentiometry technique. It was found that, under the solvothermal condition, the graphene oxide reduced by p-phenylenediamine oligomers was observed to have higher electrical capacitance than that reduced by hydrazine. The improved electrical capacitance can be attributed to that p-phenylenediamine oligomers are the more effective spacers for graphene layers; and they could also provide some pseudo-capacitance to the graphene oxide composite based on their conjugate structure. The results imply that graphene oxide modified by diamine oligomers has a good potential in energy storage devices.