We demonstrate a facile and low-cost one-step method for the fabrication of porous carbon aerogel (CA)/NiO composites by pyrolysis of sodium carboxymethyl cellulose aerogels via a sol-gel and freeze-drying process. The structure and morphology of CA/NiO composites are characterized by scanning electron microscopy, X-ray diffraction and a nitrogen adsorption method. The magnetic properties are characterized using a vibrating sample magnetometer. The resultant CA/NiO composites possess an interconnected three-dimensional structure, high specific surface area of up to 175.05 m(2)/g and saturation magnetization of 3.14 emu/g. The CA/NiO composites present excellent electrochemical performance for supercapacitors, which exhibit a specific capacity of up to 81.67 mAh/g at a current density of 0.5 A/g in a 6 M KOH electrolyte solution. In addition, the CA-1.0 electrode shows excellent electrochemical cycling stability after 5000 charge/discharge cycles, with 94.5% capacity retention. The present study highlights new opportunities for CA/NiO composites to achieve advanced supercapacitor devices for energy storage and conversion. (C) 2017 Elsevier B. V. All rights reserved.