In this research, carbon nanorods/fibers materials were successfully synthesized from sulphur-reduced graphene oxide (RGO-S) composite by using an improved Hummers' method. Morphological, structural, compositional and textural characterization of the composite material were obtained via scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The electrochemical performance of the composite sample as a promising supercapacitor electrode revealed a peak specific capacity of 113.8 mAh g(-1) at 0.5 A g(-1) estimated via GCD curves in 6 M KOH aqueous electrolyte. The half-cell could retain a columbic efficiency of about 98.7% with a corresponding energy efficiency of about 98.5% over 2000 constant charge/discharge cycle at a specific current of 5 A g(-1). Remarkably, an assembled hybrid device with carbonized iron cations (C-FP) and the RGO-S composite delivered high energy and power densities of 35.2 Wh kg(-1) and 375 W kg(-1) at 0.5 A g(-1) within a 1.5 V operating potential, respectively. A good cycling stability performance with an energy efficiency of 99% was observed for the device for up to 10,000 cycling at a specific current of 3 A g(-1). (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.