lambda-MnO2 nanoparticles have been successfully synthesized using macromolecules like starch and dextrose. The X-ray diffraction pattern shows the cubic structure of the lambda-MnO2. Morphological studies show the synthesized particles to be of nanospherical structure. The FTIR spectrum confirms the presence of Mn-O bonds. From the charge-discharge analysis lambda-MnO2 was found to exhibit the highest specific capacitance of 384 F g(-1) at a specific current discharge of 1 A g(-1). The symmetric aqueous supercapacitor device exhibits the 44 F g(-1) at a specific current discharge of 1 A g(-1). We have obtained higher specific capacitance for lambda-MnO2 in three electrode cell configuration and two electrode supercapacitor cells. This is higher than previous reports of lambda-MnO2 three electrode cell and two electrode systems. All the three electrochemical measurements (cyclic voltammetry, galvanostatic charge-discharge, and impedance) proved that the lambda-MnO2 was a good electrode material for a supercapacitor.