Tamarindus indica leaf extract was used as a bio-reductant in this study to synthesize zinc oxide nanoparticles (ZnO-NPs) blended with activated carbon for possible use in electrochemical energy conversion systems. The electrochemical behavior of the Tamarindus indica activated carbon (TIAC) and nanostructured ZnO composite mixture was also investigated using electrochemical impedance spectroscopy with 0.1 M Na2SO4 as the electrolyte. The wurtzite (hexagonal) form of the herb assisted synthesis of ZnO-NPs with size 35 nm. At a scan rate of 5 mV/s, the prepared AC-ZnO nanocomposite electrode has a specific capacitance of 275.3 F/cm2 . The electrodes specific capacitance decreased with increase of zinc oxide substance. The nanocomposites improved electrochemical behavior can be attributed to the activated carbons and electroactives high electrical conductivity.