The influence of the addition of amorphous tantalum oxide (Ta2O5) on electrochemical capacitor performance of molybdenum nitride(Mo2N) was investigated. gamma-Mo2N/Ta2O5 composite electrode materials have been synthesized using temperature-programmed reduction (TPR) the mixture Of MoO3 and amorphous Ta2O5 with ammonia gas. The materials were physically and chemically characterized by X-ray diffraction (XRD), scanning electron microcopy (SEM), and cyclic voltammetry (CV). Typical CV characterization of the materials indicated fast kinetics for charge-discharge process as well as good kinetic reversibility. The addition of amorphous tantalum oxide not only increased the electrochemical capacitance value of the materials, but also widened its potential stability window. (c) 2005 Elsevier B.V. All rights reserved.