<p>Supercapacitors are recognized as crucial charge storage devices, yet there remained significant scope for improving electrode materials to enhance their performance. This study investigated the potential of composite materials comprising copper sulfide (CuS) and nickel oxide (NiO), referred to as CuS@NiO, as an efficient positrode material to improve supercapacitor performance. To the best of available knowledge, this research represented the first systematic attempt to optimize the composition of CuS@NiO composites for energy storage applications. The optimization of CuS@NiO composites was achieved through a hydrothermal synthesis method by varying the concentration of CuS within the composite. The resulting CuS@NiO exhibited a unique combination of flower-like NiO and sheet-like CuS morphologies. Electrochemical tests, including voltammetric cycling and constant-current charge–discharge, demonstrated that the CuS@NiO composite offered higher charge storage capacity and energy density compared to individual CuS and NiO electrodes. The composite electrode achieved a specific capacity of 392 Cg¹ (980 Fg¹) at 1 Ag¹ and exhibited superior rate capability with a capacity retention of 61% at 10 Ag¹. Electrochemical impedance spectroscopy results indicated a lower intrinsic resistance (0.4 ohms) and higher ionic conductivity (0.56 × 10^⁻4 Scm^⁻1) for the composite. The assembled supercapacitor device, CuS@NiO//Graphite mixed activated charcoal, demonstrated an energy density of 44 Whkg^⁻1 at a power density of 0.825 kWkg^⁻1. It maintained cyclic stability, retaining 80.1% of its initial performance and a Coulombic efficiency of 77.6% after 5000 cycles. These findings highlighted the potential of the CuS@NiO composite as an advanced electrode material for high-performance supercapacitors, addressing the need for enhanced energy storage solutions.</p> Graphical abstract <p></p>