In this work, we presented a novel approach to synthesize nitrogen-doped porous carbon materials via a three-step fabrication process using citric acid as the carbon source and urea as the nitrogen source. Firstly, hydrochar was synthesized by a microwave-assisted hydrothermal method using citric acid and urea and as the reactants. The hydrochar was then subjected to high-temperature carbonization in Ar atmosphere followed by KOH activation, giving nitrogen-doped porous carbon materials. The morphology, structure, and textural properties of the carbons were investigated by SEM, TEM, N-2 sorption isotherms, and XPS. The as-prepared porous carbon possesses a high BET surface area of 2397 m(2) g(-1) and an average pore size of 1.8 nm. Such N-rich porous carbon shows outstanding capacitive performance (365 F g(-1) at 0.5 A g(-1)), good rate capacitive behavior, and excellent cycling stability, indicating a great potential for supercapacitors. (C) 2015 Elsevier Ltd. All rights reserved.