The special characteristics of microplasma such as microscale geometry, atmospheric operation, self-organization property, and high radical density are suitable for the synthesis of nanoparticles. Trimanganese tetroxide (Mn3O4) nanoparticles (NPs) were synthesized through plasma reduction mechanism by the use of sustainable, rapid, and microplasma array method at atmospheric conditions in a single step. 96.10% reaction yield of hausmannite Mn3O4 NPs were gained by the reduction of potassium permanganate (KMnO4) precursor solution in the presence of radicals in the microplasma discharge with a processing time of 30 minutes. The structure, oxidation state, morphology, composition, and specific surface area of synthesized particles were determined by XRD, FTIR, XPS, FE-SEM with EDX, HR-TEM, and BET characterization techniques. Spherical polydisperse particles with high surface area (304.01 m(2) g(-1)) and narrow distribution were obtained. The performance of synthesized Mn3O4 NPs as an electrode material for supercapacitor application was analyzed by electrochemical workstation, which exhibited a high specific capacitance of 144.5 Fg(-1) at a current density of 0.5 Ag-1 and the electrode material retained 43.54% of its initial capacitance after 1500 cycles. The asymmetric performance of Mn3O4 NPs as one of the electrode materials exhibited high cyclic stability with 100% retention capacitance with an energy density of 3.33 Wh kg(-1) at 0.1 Ag-1 and high power density of 422.5 W kg(-1) at 0.5 Ag-1, respectively. The present study gives new perspectives on a simple, efficient, eco-friendly, and powerful microplasma array method for the coalescence of Mn3O4 NPs and the analysis of electrochemical behavior of corresponding NPs.