A novel nanocomposite composed of gold nanoparticles, polyaniline (PANI) and hematite (alpha-Fe2O3) with core-shell structure has been successfully synthesized through a three-step process. Firstly, alpha-Fe2O3 cores were prepared by the forced hydrolysis of FeCl3. And then, aniline was polymerized in the suspension of alpha-Fe2O3. x Finally, a surface reduction oxidation was carried out between composite carriers and chloroauric acid to obtain the three-component nanocomposites. The morphology, crystalline structure and optical properties of the nanocomposites were measured by using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrometer and Ultraviolet-visible (UV-vis) spectrophotometer. The results showed that the surface of alpha-Fe2O3 cores was coated by PANI to form core-shell structure, and Au nanoparticles were deposited on the outer surface of PANI. The average sizes of immobilized Au were 5.6 and 8.1 nm respectively. In the degradation of Rhodamine B in the presence of NaBH4, the as-prepared nanocomposites exhibit an excellent catalytic activity, and the conversion rate of Rhodamine B reached 100% in 7.5 min. (C) 2012 Elsevier B.V. All rights reserved.