Nickel oxide (NiO) nano particle is synthesized by Ultrasound assisted one pot method and thus synthesized nano NiO is mixed with poly(vinyl alcohol) (PVA) to prepare the PVA/NiO nanocomposite. The influence of the composition on the structural modification on the composite is evaluated. The particle size and morphology of NiO nano material is confirmed by HRTEM. The structure and properties of the PVA/NiO nanocomposite material are characterized by FTIR, XRD, UV-Visible spectroscopy, DSC, TGA, and HRTEM. The synthesized PVA nanocomposite underwent hydrolytic oxidation reaction assisted by the effect of nano-sized NiO. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 1666-1674, 2010