AbstractNovel photochromic composites based on biopolymers (polyvinyl alcohol, starch) and Mo4O11 and W18O49 as the fillers were obtained and characterized. To improve the photochromic properties, molybdenum and tungsten oxide sols were treated by an underwater diaphragm discharge to obtain binary structures of the MoOx/WOx and WOx/MoOx (2 < x < 3) types. The formation of such oxides was confirmed by TEM, EDX, XRD analysis, and Raman spectroscopy data. Plasma treatment is increased the color intensity and reversibility. The modified sols were incorporated into polymer matrices. Spectral studies have shown that the color of photo‐colored composites depends on the chemical structure of the polymer matrix. Mechanical tests have shown the possibility of obtaining hardened or plastic composites depending on the concentration and nature of the filler.Highlights Photochromic polymer composites with W18O49 and Mo4O11 as fillers were obtained. Diaphragm discharge used as a tool for sol modification. WOx/MoOx and MoOx/WOx structures have improved photochromic properties. Color of irradiated polymer composites depends on chemical structure of polymer. Mechanical properties are determined by the polymer filler concentration.