This study reports the electrochemical performance and stability of MnO x -multiwall carbon nanotubes (MWCNTs) nanocomposite/Ni pseudocapacitor electrodes fabricated by a modified electrophoretic deposition (EPD) method. The nanocomposite electrode consisting of highly dispersed manganese oxide on MWCNTs was synthesized by a redox titration method at room temperature. The electrochemical properties of the electrode were demonstrated by cyclic voltammetry. The mean specific capacitances at a constant scan rate of 100 mV/s of MnO x -MWCNTs nanocomposites without and with heat treatment at temperatures 150, 200, and 250 C for 2 h are 378, 402, 445, and 469 F/g, respectively, which indicate an increase with increasing annealing temperature. During stability tests, the as-grown MnO x -MWCNTs nanocomposite electrode can preserve 80% of its original capacitance after 6000 cycles of operation which can be increased to 86% after annealing at 200 C for 2 h. The EPD MnO x / MWCNTs coaxial nanocomposite pseudocapacitors with manganese oxide ionized by H þ ion process exhibit high specific capacitance, fast reaction rate, high stability, and have high potential for practical applications.