Asymmetrical electrochemical capacitors using heteropoly acid (HPA) electrolytes and RuO2-graphite electrodes were investigated. The fabricated devices have a working voltage window of 0-1.4 V and can be discharged more efficiently than conventional symmetrical capacitors. Pseudocapacitance from HPA has enhanced the total capacitance of these devices. HPAs have been shown to be able to both function as an electrolyte and to contribute to pseudocapacitance.