The effect of iodine doping on the electrochemical performance of activated carbons for non-aqueous symmetric and asymmetric hybrid supercapacitors was investigated. The incorporation of iodine via high energy mechanical milling techniques significantly modified the physical and electrochemical properties of activated carbon precursors. The increasing amount of iodine into carbons leads to a unique combination of lower surface area coupled with higher volumetric and gravimetric electrochemical capacitance. Iodine modification of the carbon resulted in a 100% increase in volumetric capacitance. This improvement was a result of improved non-faradaic capacitance and the development of faradaic capacity.