Nitrogen-doped hierarchical porous carbons (NHPCs) with controllable nitrogen content were prepared via a template-free method by direct carbonization of melamine-resorcinol-terephthaldehyde networks. The synthetic approach is facile and gentle, resulting in a hierarchical pore structure with modest micropores and well-developed meso-/macropores, and allowing the easy adjusting of the nitrogen content in the carbon framework. The micropore structure was generated within the highly cross-linked networks of polymer chains, while the mesopore and macropore structure were formed from the interconnected 3D gel network. The as-prepared NHPC has a large specific surface area of 1150 m(2).g(-1), and a high nitrogen content of 14.5 wt.%. CO2 adsorption performances were measured between 0 degrees C and 75 degrees C, and a high adsorption capacity of 3.96 mmol.g(-1) was achieved at 1 bar and 0 degrees C. Moreover, these nitrogen-doped hierarchical porous carbons exhibit a great potential to act as electrode materials for supercapacitors, which could deliver high specific capacitance of 214.0 F.g(-1) with an excellent rate capability of 74.7% from 0.1 to 10 A.g(-1). The appropriate nitrogen doping and well-developed hierarchical porosity could accelerate the ion diffusion and the frequency response for excellent capacitive performance. This kind of new nitrogen-doped hierarchical porous carbons with controllable hierarchical porosity and chemical composition may have a good potential in the future applications. (C) 2016 Elsevier Inc. All rights reserved.