An ultrathin composite film containing both poly(diallyldimethyl ammonium chloride) (PDDA) and hexa(sulfobutyl)fullerenes (C-60-HS) has been fabricated by the electrostatic layer-by-layer self-assembly technique. UV-Vis spectra showed a continuous deposition process of PDDA and C-60-HS. The film structure was characterized by small angle X-ray diffraction measurement and AFM image. The nanothick film showed an effective third-order nonlinear refractive index n(2) = 1.56 x 10(-8) esu. (C) 2003 Elsevier B.V. All rights reserved.