<p>This study presents a simple solid-state reaction technique for synthesizing different quantities of Zn-doped Ca₃Co₄O₉ (CCO) as an electrode for supercapacitors. The confirmation of phase formation has been established through the analysis of the powder X-ray diffraction (XRD) pattern of the samples. The dispersion and shape of the Zn-doped CCO samples were examined using scanning electron microscopy (SEM). The surface areas and pore volumes of the product were measured by analysing the N₂ adsorption–desorption isotherm curves. The findings demonstrate that the incorporation of Zn into CCO resulted in improved pore volumes, a larger specific surface area, and decreases particle size. Based on the results obtained from X-ray photoelectron spectroscopy (XPS), it has been shown that these materials exhibit a combination of Co²⁺, Co³⁺, Co⁴⁺, and Zn²⁺ valence states. TGA was used to evaluate the mixture's thermal stability at a rate of 20&#xa0;°C per minute. To investigate the electrochemical characteristics, galvanostatic charge discharge (GCD), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) approaches have been used. The examined samples demonstrated pseudocapacitive behaviour, as seen by the cyclic voltammetry (CV) curves. The Ca₃Co_3.8Zn_0.2O₉ electrode material is found to have a specific capacitance (C_s) of 963.98 F/g at a current density of 1 A/g. Furthermore, the symmetric supercapacitor that was fabricated showed a power density of 225 W/kg and an energy density of 30.12 Wh/kg. The investigation of electrode stability over a span of 2000 cycles revealed an excellent retention rate of 99.62% and a perfect coulombic efficiency of 100%. The observed results suggest that Zn-doped Ca₃Co₄O₉ presents promising potential as an electrode material for supercapacitor applications.</p> Graphical Abstract <p></p>