Flexible electronics require materials with high breakdown strength, high dielectric constant, and thermal stability. These conditions are met by composites based on polymers and metal oxides. In this article, we present a new onestep method for producing composites based on water-soluble polyvinyl alcohol (PVA) and metal oxides (AlOOH, CuO, and ZnO). The source of oxides is underwater plasma. The oxides are introduced into the polymer matrix when plasma is exposed to the polymer solution. The results of X-ray, IR, and SEM analysis showed that metal oxides are embedded in the polymer. Differential scanning calorimetry measurements have shown that the glass transition temperature depends on the oxide being incorporated. The electrical properties of polymer composites were studied by current-voltage characteristics. Dielectric properties were measured in the range of 25-10 6 Hz. The properties of obtained PVA + metal oxide showed that using underwater plasma is a suitable method for producing composites for electronic devices.