We demonstrate a simple synthesis of N-doped porous carbons (NPCs) with nanofiber-like structure via one-step direct carbonization/KOH activation of poly (aniline-co-p-phenylenediamine) (P(ANI-co-PPDA)) at temperatures from 600 to 900 degrees C in NZ atmosphere. The increase of heat treatment temperature results in an increased specific surface area (from 776 to 2022 m(2) g(-1)) while decreased nitrogen content (from 6.96 to 1.18 wt.%). At 700 degrees C, the resultant NPCs (denoted as NPC-700) show a high surface area (1513 m(2) g(-1)), high N content (6.43 wt.%) and nanofiber-like morphology. In 6M KOH electrolyte, NPC-700 electrode has a capacitance as high as 316 Fg(-1) at 1.0 Ag-1, and remains 167 Fg(-1) at 10.0 Ag-1. Besides, NPC-700 electrode exhibits good cycling stability, with capacitance retention of 81.6% after 5000 cycles at 1.0 A g(-1). The simple synthesis route and high electrochemical performance of the NPCs show great potential in supercapacitor application. (C) 2016 Elsevier Ltd. All rights reserved.