Thin films of sprayed nickel–manganese ferrite i.e. Ni_xMn_1−xFe₂O₄ (x = 0.2, 0.4, 0.6, 0.8) were synthesized onto stainless-steel substrate and envisaged for electrochemical supercapacitor application where surface morphology was influenced by ‘x’ factor; confirmed from the scanning electron microscopy digital photo-images and energy dispersive X-ray analysis, respectively. The spinel-type rice-like crystallites of Ni_xMn_1−xFe₂O₄ were 70–80 nm in lengths and 20–30 nm in diameters. Cyclic-voltammograms of Ni_xMn_1−xFe₂O obtained for different ‘x’ values i.e. morphologies, were used to figure-out the change of the specific capacitance (SC) for different scan rates in 1 M KOH electrolyte. The 147, 120, 131, 185 F g⁻¹ SC values for 0.2, 0.4, 0.6, 0.8 ‘x’ values were obtained at 5 mV s⁻¹ scan rate. Electrochemical impedance spectroscopy measurements of Ni_xMn_1−xFe₂O₄ film electrodes were performed for knowing the charge transport kinetics where composite i.e. 0.4 and 0.6 ‘x’ valued electrodes confirmed least performance than 0.2 and 0.8 ‘x’ values which could be attributed to availability of number of the surface charges.