We demonstrate the sonochemical synthesis of multiwalled carbon nanotubes (MWCNTs) and MoO3 hybrids for an application in supercapacitor (SC) electrodes. The MoO3 nanodots with the diameter of <10 nm are uniformly deposited on the surfaces of MWCNTs as characterized by TEM and STEM images. The specific capacitance of 103 F g(-1) in MoO3/MWCNT hybrids is two times higher than 42 F g(-1) of the pristine MWCNTs and four times higher than 22 F g(-1) of MoO3. Moreover, hybrid electrodes show a good rate capability of >90% retention up to 2.12 A g(-1) and cyclic stability of 80% retention during 1000 cycles of charge/discharge because of the mechanical stability of the MWCNTs and the good contact between the MoO3 and MWCNTs. The energy density of MoO3/MWCNT hybrids is evaluated to be 38.7 Wh kg(-1) by using an organic electrolyte. Therefore, the hybridization of MWCNTs and redox-active MoO3 nanodots provides a rational design strategy to overcome the critical challenges of pseudocapacitors such as poor rate and cycle stability, while improving the low specific capacitance of electric double layer capacitors (EDLCs). Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.