A novel nanocomposite based on poly(N-octadecyl-2-ethynylpyridinium bromide) (PNOEtPyBr) and Mg0.04Nb1.66O5 nanosheets is synthesized by the method of exfoliation-reflocculation. The XRD data of the nanocomposite indicates the formation of Mg0.04Nb1.66O5 nanosheets/PNOEtPyBr nanostructure with an interlayer expansion of 4.6 nm along a direction perpendicular to the Mg0.04Nb1.66O5 nanosheets. Formation of this nanocomposite is further supported by the results obtained by FT-IR spectroscopy and thermogravimetry. This nanocomposite exhibits interesting dielectric properties with a dielectric constant of 18.7 F/m at 1000 Hz and 25 degrees C, which are also compared to the properties of HMg0.34Nb1.66O5 and PNOEtPyBr. (c) 2005 Elsevier Inc. All rights reserved.