Nanostructured bismuth oxide was prepared in silica media by a modified sol-gel method using of tetraethylorthosilicate and hydrated bismuth nitrate. The calcination temperature was determined by thermal gravimetric analysis. The morphology, crystal and electronic structure of composites were characterized by powder X-ray diffraction, XRD, scaning electron microscopy, SEM, transmission electron microscopy, TEM, UV-vis diffuse reflectance spectroscopy and Mott-Schottky analysis. Cyclic voltammetry and galvanostatic charge and discharge curves were used to study the electrochemical and capacitive behaviors of dispersed Bi2O3 nanoparticles in silica matrix in 1.0 M NaOH. Our studies showed that by decreasing in the amount of Bi2O3 in nanocompsite, the normalized capacitance of bismuth oxide increases. (C) 2014 Elsevier Ltd. All rights reserved.