Supercapacitors have attracted great attention due to their rapid charge-discharge rates, long cycle life and high power density. Binary metal oxides, specially spinel structures as supercapacitor have been investigated to show better electrochemical performances than single component oxides owing to their available multiple oxidation states. In this paper, a simple and scalable process has been developed for synthesizing ultrafine ZnMn₂O₄/carbon nanostructures through a solution combustion method. Effect of polyethylene glycol (PEG) weight percentage with low and high molecular weights, as carbon source and pore size controller, on the structure and physical properties of the ZnMn₂O₄/carbon were investigated in details and well characterized using XRD, FESEM, TEM, HRTEM and N₂ adsorption/desorption. Electrochemical characterization of the oxide electrode indicated unique combination of pseudocapacitance and battery behaviors, exhibiting large capacitances (> 150 F/g) and an intriguing dependence on electrolytes. The charge-transfer mechanisms have been characterized by in-situ XRD and X-ray absorption analyses.