Polymer/layered-silicate hybrids nanocomposites have attracted strong interest in today's materials research, as it is possible to achieve impressive enhancements of material properties compared to the pure polymers. In the present investigation, at first, Cloisite Na+ was modified by protonated form of natural L-methionine amino acid via ion-exchange reaction to created chiral organonanoclay. Gallery spacing, interlamellar structure, and thermal stability of this novel chiral organonanoclay have been characterized using different techniques. Then it was used to fabrication of poly(vinyl alcohol) (PVA)/organonanoclay nanocomposite films (NCF)s with various compositions using solution casting method by ultrasound-assisted method. The films were characterized using Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electronic microscopy, and transmission electronic microscopy (TEM). Furthermore, thermal and optical clarity properties were investigated by thermogravimetric analysis and UVvisible transmission spectra, respectively. The TEM and XRD structure study revealed a coexistence of exfoliated and intercalated organonanoclay in the PVA matrix. The addition of organoclay into the PVA origins increases in the thermal decomposition temperatures of the NCFs. This enhancement in the thermal stability is owing to the presence of organonanoclay, which act as barriers to maximize the heat insulation and to minimize the permeability of volatile degradation products to the material. At the same time, the optical clarity of PVA/organonanoclay NCFs is not decreased in comparison with that of pure PVA. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012