Polyaniline/nano-TiO2 composite was prepared by polyaniline for the surface modification of nano-TiO2 particles, and was characterized via Fourier-transform infrared spectra, UV-Vis-NIR spectrophotometer, wide-angle X-ray diffraction, thermo-gravimetric analysis and transmission electron microscope, as well as conductivity. Surface area, total pore volume and pore size distribution of nano-TiO2 particles and polyaniline/nano-TiO2 composite particles were also measured. The results of spectroanalysis illustrate that polyaniline and nano-TiO2 particles are not simply blended or mixed up. There is a strong interaction between polyaniline macromolecule and nano-TiO2 particles. Synthesized polyaniline was deposited on the surface of nano-TiO2 particles, forming a core-shell structure. The dimension of polyaniline/nano-TiO2 composite particles is in the range 25-40 nm. Polyaniline/nano-TiO2 Composite contains 38% conducting polyaniline by mass, for which conductivity reaches 0.75 S cm(-1) at 25 degreesC. (C) 2004 Elsevier B.V. All rights reserved.