An electrical conducting polyaniline/nano-SiO 2 composite was obtained by surface modification of nano-SiO 2 particles using polyaniline, and was characterized via Fourier transform infrared (FTIR) spectra, UV–vis absorption spectra, wide-angle X-ray diffraction (WXRD), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM), as well as conductivity. Surface area, total pore volume, and pore size distribution of both nano-SiO 2 particles and polyaniline/nano-SiO 2 composite particles were also measured. The results of spectroanalysis show that the composite is not a simple blend of polyaniline with nano-SiO 2 particles. An interaction exists at the interface of nano-SiO 2 particles and polyaniline macromolecule. Polyaniline/nano-SiO 2 composite contains 15% conducting polyaniline by mass, with a conductivity of 0.32 S cm −1 at 25 °C. The dimension of polyaniline/nano-SiO 2 composite particles is about 20–30 nm.