Electrochemical capacitor or supercapacitor is regarded as a solution to the mismatch between the fast growth for the power requirement of deviceand the disability of battery to discharge effectively, which is still limited by low energy densities. In this study, advanced electrode based on chemically reduced graphene film with ultrahigh energy density for supercapacitor application have been developed by the use of a simple technique.　　This study describes a novel, simple and low-cost technique to prepare a chemically-reduced graphene film for supercapacitor application. The effect of certain parameters such as temperature and period of reduction oncapacitive behavior were investigated. The produced film possesses high electrical conductivity, outstanding mechanical properties. It was investigated also as electrode and it displays an ideal capacitive behavior with high specific capacitance and a large voltage region (1.4 V) in aqueous electrolyte. Moreover, it shows an excellent cyclic stability (about 92％ of its initial response after 5000 cycles). These encouraging findings make the present material a quite promising alternative for the next generation of high-performance supercapacitors.　　To determine the best chemical reduction of graphene oxide film with hydriodic acid that gives maximum specific capacitance and results an ideal capacitive behavior, we studied the effect of two reducing systems, hydriodic acid/water and hydriodic acid/acetic acid, on the morphology and electrochemical features of reduced graphene oxide film. Using acetic acid as solvent results in high electrical conductivity (5195 S·m-1), excellent specific capacitance (384 F·g-1) and good cyclic stability (about 99% of its initial response after 1300 cycles). Using water as a solvent, results in an ideal capacitive behavior and excellent cyclic stability (about 4% increase of its initial response after 1300 cycles).In order toachieve a high energy density and enhance the capacitive behavior of the graphene film electrode. We pioneered a simple step-by-step chemical reduction methods by altering two different reducing systems with the order hydriodic acid-water in Hydriodic acid-acetic acid (HI-H2O/HI-AcOH), and the reverse order (HI-AcOH/HI-H2O).The produced graphene film possesses high specific capacitance (~524 F·g-1) which is close to the theoretical value, high electric conductivity (~ 4630 S·m-1). The operation voltage isenlarged to 1.4 V in spite of using aqueous electrolyte, yielding a maximum energy density (~165.4 Wh·kg-1) at a power density (~ 162.4 W·kg-1). Such outstanding results made a supercapacitor comparable to battery in terms of energy density. This paper proposed a promising solution in developing energy storage devices with a high energy and power densities for wide range applications.