Prismatic polymer monolithic capacitor structure including multiple interleaving radiation-cured polymer dielectric layers and metal layers. Method for fabrication of same. The chemical composition of polymer dielectric and the electrode resistivity parameters are chosen to maximize the capacitor self-healing properties and energy density, and to assure the stability of the capacitance and dissipation factor over the operating temperature range. The glass transition temperature of the polymer dielectric is specifically chosen to avoid mechanical relaxation from occurring in the operating temperature range, which prevents high moisture permeation into the structure (which can lead to higher dissipation factor and electrode corrosion). The geometry and shape of the capacitor are appropriately controlled to minimize losses when the capacitor is exposed to pulse and alternating currents.