The nanosized Mn3O4 particles were prepared by microwave-assisted reflux synthesis method. The prepared sample was characterized using various techniques such as X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Raman analysis, and transmission electron microscopy (TEM). Electrochemical properties of Mn3O4 nanoparticles were investigated using cyclic voltammogram (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge analysis in different electrolytes such as 1 M KCl, 1 M Na2SO4, 1 M NaNO3, and 6 M KOH electrolytes. XRD pattern reveals the formation of single-phase Mn3O4 nanoparticles. The FT-IR and Raman analysis also assert the formation of Mn3O4 nanoparticles. The TEM image shows the spherical shape particles with less than 50 nm sizes. Among all the electrolytes, the Mn3O4 nanoparticles possess maximum specific capacitance of 94 F g−1 in 6 M KOH electrolyte calculated from CV. The order of capacitance obtained by various electrolytes is 6 M KOH > 1 M KCl > 1 M NaNO3 > 1 M Na2SO4. The EIS and galvanostatic charge–discharge results further substantiate with the CV results. The cycling stability of Mn3O4 electrode reveals that the prepared Mn3O4 nanoparticles are a suitable electrode material for supercapacitor application.