MnxCu1-xLa0.12Fe1.88O4 spinel nanocrystals, (x = 0, 0.25, 0.5, 0.75 and 1) have been synthesised by the echo-friendly route using co-precipitation strategy and examined utilizing X-ray diffraction (XRD), Fourier transform Infrared (FTIR) and thermal analysis using DTA/TGA. XRD plots proved the complete emersion of the solitary-phase Nano-spinel for all the scrutenized samples. Samples' crystallite size R declined with x. FTIR confirmed the evolution of Nano-spinel phase. DTA/TGA showed decrease in sample weight giving largest weight loss around ≈ 22 % and affirmed the complete emergence of Nano-spinel phase. Cyclic voltammetry and galvanostatic charge/discharge measurements were adopted to investigate the electrochemical merits of MnLa0.12Fe1.88O4 spinel nanoparticles in 1 M KOH electrolyte solution. MnLa0.12Fe1.88O4 spinel nanoparticles exhibited specific capacitance of 1500 mF/g at 50 mV/s. Nearly, rectangular shape of cyclic voltammetry curve revealed that electric double layer capacitance was dominated. The study presents a promising application of MnLa0.12Fe1.88O4 spinel nanoparticles as electrode materials for energy storage and sensing. Nyquist plots for MnLa0.12Fe1.88O4 spinel nanoparticles in the frequency range from 1.0 Hz to 20 kHz. MnLa0.12Fe1.88O4 spinel nanoparticles retains low value of solution resistance (Rs) as 12.9 Ω.