Supercapacitor technology is a promising development in energy storage devices. Despite its potential as an anode material, nickel sulfhide (Ni3S2) utilization for practical application in energy storage devices is limited owing to its weak conductivity. Subsequently, it can be improved in the alteration of electronic properties by the introduction of impurities and surface defects. In this work, sulphur vacancy was created in hydrothermally synthesized nickel sulphide by inserting neodymium ions. The synergetic action of the dopant and produced sulphur vacancy have an effect on the electronic properties. The electrocatalytic behavior of the fabricated materials was also enhanced by adding polyethylene glycol, which was used as a reducing agent to promote the formation of sulphur vacancy. Examine the impact of neodymium doping concentration in nickel sulphide on the enhanced electrical structure of nickel sulphide by comparing electrocatalytic materials doped with varying amounts of neodymium. One of the 0.3-Nd doped nickel sulphide (0.3-NdNS) electrodes showed the best electronic properties, with a specific capacitance (Cs) of 2122.64 F g−1 at 1 A g−1 and energy density of 119.25 Wh Kg−1. The practical potential of the symmetric nature of 0.3-NdNS electrode material was examined with two electrode systems, exhibiting the specific capacitance (Cs). Our results suggest optimized 0.3-NdNS electrode materials have great potential for supercapacitor applications.