The porous nanocarbons supported by acid-treated multiwall carbon nanotubes (PC@ACNTs) were prepared by the combination of the hydrothermal polymerization of glucose on ACNTs, carbonization under N-2 protection and final activation with ZnCl2. The materials were characterized by transmission electron microscopy, X-ray powder diffraction and Raman spectra. The results indicated that the ACNTs distributed uniformly into the framework of the porous carbon. The composites showed the high BET specific surface area up to 1712 m(2) g(-1) and good conductivity. The electrochemical measurements indicated that the composites processed good performances for electrochemical energy storage (210 F g(-1) at 0.5 A g(-1)), and high stability (>99.9%), much higher than the corresponding ACNTs, porous carbons and the samples prepared by using raw MWCNTs as source. The good performance of PC@ACNTs composites was relative with the synergy of good conductivity of ACNTs and large specific surface areas of PC. (C) 2013 Elsevier Ltd. All rights reserved.