The CuO nanoparticle doped poly(vinyl alcohol) (PVA) nanocomposite films were prepared by the solution casting method. The structure of the prepared CuO nanoparticles and PVA nanocomposite films were confirmed by FTIR spectroscopy and XRD. The (101) crystal plane of PVA was observed at 19.8° in XRD. The size of the CuO nanoparticles was determined as 20 nm using Scherrer's formula. It was further confirmed with HRTEM. The surface morphology of the nanocomposite films was investigated using SEM. The optical properties of the prepared CuO nanoparticles and PVA nanocomposite films were analyzed by UV–Visible spectroscopy. The band gap of PVA was decreased after the incorporation of CuO in PVA. The thermal stability of the pure PVA and its nanocomposites was examined using TGA to assess their thermal degradation temperature at five different heating rates. The thermal stability of PVA nanocomposites was increased as compared with pure PVA. The non‐isothermal degradation kinetic studies were also carried out to determine the energy of activation (Ea) for the degradation process using four different kinetic models. The tensile strength and Young's modulus of PVA nanocomposite films were notably increased with the increasing concentration of CuO nanoparticles. POLYM. COMPOS., 40:3737–3748, 2019. © 2019 Society of Plastics Engineers