High energy density Li-ion hybrid electrochemical capacitors (Li-HEC) are fabricated with 3 D architectured high surface area porous carbon (HSPC) derived from the poly(acrylamide-co-acrylic acid) potassium salt in a single step without any activating agent. The obtained HSPC exhibits high specific surface area of 1490 m2 g−1 and characterized with several analytical techniques. Li-HEC is fabricated with insertion type Li4Ti5O12 anode by adjusting the mass balance based on the single electrode performance with Li. The Li-HEC delivered the maximum energy density of ∼55 Wh kg−1, which is much higher than commercially available activated carbon (∼36 Wh kg−1). Further HSPC based Li-HEC delivered excellent cycleability and rendered ∼87% of initial value after 2000 cycles.