To investigate La2ZnOx nanoparticles, ZnO is partially substituted by lanthanum oxide (La2O3) using a tartaric acid precursor. The prepared nanoparticles were reinforced in the polyvinyl alcohol (PVA) with different content and the films were obtained by casting method. The impact of the nanoparticles in the polymer structure and the thermal stability of the films were studied by X-ray diffraction and TGA-DTA techniques. Optical parameters were investigated using the absorbance and transmittance spectra obtained from the UV–visible spectrophotometer. Optical bandgap decreases, whereas the refractive index and optical conductivity improved with the addition of La2ZnOx nanoparticles in the polymer matrix. PVA-La2ZnOx films with enhanced futures are promising for organic-electronic applications. © 2022 Elsevier B.V.