Graphene oxide derived from palm kernel shells (rGOPKS) and polyacrylonitrile (PAN) were electrospun into composite fiber mats and evaluated as supercapacitor electrode materials. Their morphologies and crystalline properties were examined, and chemical interactions between rGOPKS and PAN were investigated. The diameters of individual fibers in the rGOPKS/PAN composite mats ranged from 1.351 to 1506 μm and increased with increasing rGOPKS content. A broad peak centered near 23° in the X-ray diffraction (XRD) pattern of rGOPKS corresponded to the (002) planes in graphitic carbon. Characteristic rGOPKS and PAN peaks were observed in the XRD patterns of all the composite fibers, and their Fourier-transform infrared (FTIR) spectra indicated hydrogen bond formation between rGOPKS and PAN. The composite fiber mats had smooth and homogeneous surfaces, and they exhibited excellent flexibility and durability. Their electrochemical performance as electrodes was assessed, and a maximum specific capacitance of 203 F g −1 was achieved. The cycling stability of this electrode was excellent, and it retained over 90% of its capacitance after 5000 cycles. The electrode had an energy density of 17 W h kg −1 at a power density of 3000 W kg −1 . Dielectric results showed a nanofiber composite dielectric constant of 72.3 with minor leakage current (tan  δ ) i.e. , 0.33 at 51 Hz. These results indicate that the rGOPKS/PAN composite fibers have great promise as supercapacitor electrode materials. Graphene oxide derived from palm kernel shells (rGOPKS) and polyacrylonitrile (PAN) were electrospun into composite fiber mats and evaluated as supercapacitor electrode materials.