Thus, the obtained compound has got the N-doping content of 9.83 at. % and accomplished the specific capacitance of 243 F g -1 at 1 A g -1 in 1 M H2SO4 solution due to the oxygen containing hydroquinone and N-doping. Therefore, not only the N-doping but also the presence of oxygen containing functionalities enhance the capacitive performance. This is attributed to the fact that the oxygen containing functionalities such as hydroxy group interact with hydroxide ions to generate the negatively charged oxyanion in basic electrolyte. On the other hand, if the electrochemical process is performed in acidic electrolyte, then carbonyl oxygen or epoxy oxygen interact with H + from the acidic electrolyte to form oxonium ion. Among the N-doped graphene synthesized from three various conditions such as alkaline (strong and weak) and neutral, the N-doped graphene obtained under weakly alkaline condition has reached the N-doping level of 8.56 atomic % and the boosted specific capacitance of 399 F g -1 at 1 A g -1 in 6 M KOH solution. This is because of the fact as the reaction was carried out at strongly alkaline condition, the graphene sheets are more prone to restack and the residual oxygen functionalities increased but the content of nitrogen reduced which diminishes the electrochemical performance of N-doped graphene. It was observed that the content of nitrogen diminishes with increase of sodium hydroxide suggesting that the pH has profound influence of the nitrogen content as well as the capacitance. The symmetric supercapacitor investigations revealed that it exhibits an excellent stability with 92.8% retention over 10000 cycles at 5 A g -1 . Dai et al. investigated the synthesis of N-doped graphene using hydrazine hydrate as the nitrogen source under hydrothermal condition at 160 °C for 3 h [530]. The specific capacitance of N-doped graphene calculated at 1 A g -1 is 390 F g -1 which is greater than RGO without N-doping (207 F g -1 ) in 2 M KOH electrolyte which might be ascribed to the fact that the SBET of the former is found to be 203 m 2 g -1 which is relatively higher than the latter (111 m 2 g -1 ). The N-doped based symmetric supercapacitor delivered an energy density of 55 Wh kg -1 at a power density of 1800 W Kg -1 in BMIMBF4 electrolyte with the working voltage of 3.5 V. Additionally, superior cyclability with 97% of the capacitance was retained from the initial value after 20000 cycles along with the same symmetric device could power 4