It has been reported that the reaction temperature has significant influence on the porosity which in turn affects the electrochemical performance. For instance, the B-doped graphene was prepared by Fried-ice method and the subsequent thermal annealing at three different temperatures . Among the three different temperatures, the B-doped graphene obtained at 800 °C has achieved the high specific capacitance of 281 F g -1 at 1 A g -1 in 2 M H2SO4 aqueous solution as the electrolyte. Prior to understand the cause behind the high electrochemical performance, it is necessary to realise the impact of annealing temperatures on the porosity as well as the capacitive performance. The minimal content of boron is observed in the B-doped graphene prepared at 400 °C. If the temperature increases from 600 to 800 °C then the content of boron also increases to about 2 to 3%. This is attributed to the fact that the active defects over the graphene sheets enhanced by steam etching that permits the boron to utilize the greater number of active sites. When the temperature increased to 800 °C, then the influence of steam etching on the graphene sheet is still more pronounced. As a result, the graphene sheet got exfoliated and became porous. This suggests that the large-size graphene sheet is divided into smaller ones over which number of nanopores are apparently found. The calculated BET specific surface area for the B-doped graphene prepared at 400, 600, and 800 °C are found to be 254, 342, and 622 m 2 g -1 , respectively. The same trend is also applicable for the value of specific capacitance with respect to temperature which is in the order 800 (281 F g -1 ) > 600 (226 F g -1) > 400 (143 F g -1 ).