Here we report a 3-dimensional hierarchical porous activated carbon (HPAC) prepared from coconut fibers with KOH activation, which exhibits high-rate performance for symmetric supercapacitors. At a 4:1 mass ratio of KOH to carbonized coconut fibers, the highest specific surface area of 2898 m2 g− 1 with a pore volume of 1.59 cm3 g− 1 (30% mesopores) is successfully achieved in a 3-dimensional HPAC. As a supercapacitor electrode combined with a 6 M KOH electrolyte, a high specific capacitance of 266 F g− 1 at a current of 0.1 A g− 1 is successfully achieved and an excellent rate performance up to 76% of its capacitance is retained at a high current of 100 A g− 1. Additionally, in EMIMBF4 electrolyte, 3-dimensional HPAC electrode exhibit a high capacitance of 155 F g− 1 at 0.1 A g− 1 and 142 F g− 1 at 10 A g− 1. Owing to its excellent rate performance, 3-dimensional HPAC can deliver a high energy density of 53 Wh kg− 1 and a high power density of 8224 W kg− 1, which shows promising application potential in energy storage devices.