<p>Polyaniline (PANI) thin-film electrode is deposited onto a flexible stainless steel substrate using the cost-effective and simple solution-processed Successive Ionic Layer Adsorption and Reaction (SILAR) method. Two oxidizing agents ammonium persulfate (APS) and potassium persulfate (KPS) were employed to investigate their influence on the structural and electrochemical performance of PANI electrodes. The PANI thin films were synthesized using 10, 15, and 20 SILAR cycles, and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX), and Fourier transform infrared spectroscopy (FTIR). Electrochemical performance was evaluated through cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) studies in various acidic electrolytes (HCl, HNO₃, and H₂SO₄). PANI electrodes utilizing the oxidizing agent APS (547 F g⁻¹) exhibited superior performance compared to those using KPS (370 F g⁻¹) for 15 cycles at 50&#xa0;mV&#xa0;s⁻¹ scan rate. PANI electrodes treated with APS for 15 cycles (547 F g⁻¹) demonstrated higher performance than PANI treated with APS for 10 (530 F g⁻¹) and 20 cycles (532 F g⁻¹) at scan rate of 50&#xa0;mV S⁻¹. The specific capacitance values for the PANI-APS 15 electrodes were measured at 532 F g⁻¹ at a current density of 1&#xa0;mA&#xa0;cm⁻² in an H₂SO₄ electrolyte and maintained 61% capacitance retention after 2000 charge–discharge cycles.</p>