The facile synthesis, by electrospinning of highly conductive RuO₂ fiber mats as the conducting core of electrochemical capacitors, is reported. Electrospun RuO₂ fiber mats, calcined at 400 °C, exhibited highly porous morphologies composed of crystalline RuO₂ nano-particles with an average particle size of 10 nm. The highly conducting (σ = 288 S cm⁻¹) fiber mats were used as the basis of a hybrid electrochemical capacitor in which the fiber mats served as the conducting core for electrochemically deposited hydrate RuO₂·nH₂O overlayers. These electrochemical capacitors exhibited superior characteristics: a high specific capacitance of ∼886.9 F g⁻¹ (based on the mass of the hydrous RuO₂ coating layer) at scan rate of 10 mV s⁻¹ and high rate capability with a capacity loss of only 30% from 10 to 2000 mV s⁻¹. This is attributed to the superior electron transport pathways provided by the fiber mat core to the upper ionically conducting hydrous RuO₂ coating layer.