Nanoporous carbons obtained by selective leaching of Ti and Al from Ti2AlC, as well as B from B4C, were investigated as electrode materials in electric double-layer capacitors. Cyclic voltammetry tests were conducted in 1 M H2SO4 from 0-250 mV on carbons synthesized at 600, 800, 1000, and 1200 degrees C. Results show that the structure and pore sizes can be tailored and that the optimal synthesis temperature is 1000 degrees C. Specific capacitances for Ti2AlC CDCs and B4C CDCs were 175 and 147 F/ g, respectively, compared to multiwall carbon nanotubes and two types of activated carbon, measured herein to be 15, 52, and 125 F/ g, respectively. (c) 2005 The Electrochemical Society.